Publicly accessible
URL: http://nzetc.victoria.ac.nz/collections.html
copyright 2006, by Victoria University of Wellington
All unambiguous end-of-line hyphens have been removed and the trailing part of a word has been joined to the preceding line, except in the case of those words that break over a page. Every effort has been made to preserve the Māori macron using unicode.
Some keywords in the header are a local Electronic Text Center scheme to aid in establishing analytical groupings.
Tuatara aims to stimulate and widen interest in the natural sciences in New Zealand, by publishing articles which (a), review recent advances of broad interest; or (b), give clear, illustrated, and readily understood keys to the identification of New Zealand plants and animals; or (c), relate New Zealand biological problems to a broader Pacific or Southern Hemisphere context. Authors are asked to explain any special terminology required by their topic. Address for contributions: Editor of Tuatara, c/o. Victoria University of Wellington, Box 196, Wellington, New Zealand. Enquiries about subscriptions or advertising should be sent to: Business Manager of Tuatara, c/o. Victoria University of Wellington, Box 196, Wellington, New Zealand.
(This issue edited by
is the journal of the Biological Society, Victoria University of Wellington, New Zealand, and is published three times a year. Joint Editors:
In December, 1966, two Victoria University students, Vincent Neall and Ian Smith, were camping in a polar tent on Nussbaum Riegel in the Taylor Valley, Ross Dependency. They were members of VUWAE 11, working some distance away from the rest of this expedition.
In this setting they conceived the idea of publishing a collection of University Antarctic papers, especially those of biological character. The Victoria University of Wellington Biological Society's ‘Tuatara’ appeared especially appropriate as a journal for this purpose. In the ten years of V.U.W. Antarctic expeditions, many papers have been published in New Zealand and overseas scientific journals by V.U.W. members, but relatively few of these have been on biological topics and none to my recollection has been published in ‘Tuatara’.
While many New Zealand University students have worked in Antarctica since 1957 under various auspices, two Universities (Victoria and Canterbury) have undertaken major scientific projects in the Ross Dependency. Victoria University has at the time of writing sent eleven expeditions to various parts of the Dependency, the first in 1957. While some biology has been done by these expeditions, especially with earlier parties, in the main they have been concerned with the Earth Sciences.
Canterbury University has been sending biological parties south since 1961. Work on penguins, skuas and seals has been proceeding, and every summer during the last six years, staff, students, and technician groups, mainly from the Zoology Department of the University, have been active at Cape Royds, Cape Crozier, Cape Bird and other localities.
Of the five biological papers in this issue of ‘Tuatara’, two are written by former VUWAE members, the other three by the past and present leaders of the Canterbury Antarctic unit and one of their colleagues.
“Exploration is the Physical Expression of the Intellectual Passion”
—Apsley Cherry-Garrard.
On December 30, 1957 I drove a tractor across the sea ice from Scott Base to meet H.M.N.Z.S. ‘Endeavour’, preparing to tie up about 9 miles from the base. I was naturally keen to begin unloading the ship and to meet the members of the incoming party. After being introduced to the new party I noticed a couple of rangy youths to whom I had not been introduced, and who were obviously not members of either the wintering party or the ship's crew. ‘Who are these two young - - - -?’ I said. ‘Them—oh they're university students’, says Lyn Martin the incoming leader, and then seeing the look in my eyes hastily followed up with—‘now—don't blame me’.
There they were, the first two of them, uninvited, unheralded and unwanted. With a limited base staff, unlimited American visitors, Hillary ‘hell-bent for the pole’ and four other parties in the field, unloading and changeover problems and the possibility of Bunny Fuchs and party having to winter over at Scott Base, neither I nor anyone else was enthusiastic about supernumaries without any place in the long prepared plans.
Somehow, and I have no clear recollection of how they achieved it, these two students ‘infiltrated’ a couple of non-geological parties intending to study the lakes of the so-called dry valleys. As a result of their work during the next few weeks the dry valleys became Dry Valleys, and during the next few years probably the most intensively studied parts of the Antarctic Continent.
Webb and McKelvey the original students are 10 years older now, and approaching the peak years of their professional life, no longer students, though they can't convince me of that. The success of their work and the subsequent VUWAE expeditions have been based on two things—their personal attributes and the persistent character of See appended list, P.114.
Since 1957, ten other expeditions have gone and come. Some didn't earn unqualified approval from me for I thought their aims fragmented, but the later expeditions have had to investigate the ever-increasing number of problems that has arisen from the early surveys. Simple logic tells us that if the number of man-months of work has a limit, as it must in the New Zealand Antarctic Programme, the number of fields of enquiry can only be increased at the cost of a loss in intensity in each field. At other times it seemed that too many staff were spending too short a time down there, but this is probably a product of this fragmentation. However, I feel, if possible, that University Expeditions should consist of senior students left to their own devices once the problem has been outlined by staff in consultation with the students. The ability to sustain a scientifically productive season in the Ross Dependency unaided is a tremendous test of self-reliance as well as of research capacity. Admittedly some will drown through being thown into the deep-end, but the list of those who have emerged with great credi’ from VUWAE expeditions is impressive.
And what of the future? Every young man's first expedition is an adventure so there should be no slackening in the attraction of Antarctica. Scientifically, the problems are even more interesting now that enough data has been gathered, enough ideas formulated, to allow the synthesis which is the art of science, and the testing of the model which is the science of science. We are no longer ‘stamp collecting’ in Antarctica, and there must be an exciting future there.
But for the present, to the pioneers Webb and McKelvey, to the succeeding teams, and to the general, Professor Clark, I offer my congratulations on a remarkably long-sustained endeavour in exploration and research.
Participation In Antarctic Research by expeditions from V.U.W. began ten years ago, in 1957. Scott Base was established in December, 1956 to serve New Zealand's activities in connection with the Trans-Antarctic Expedition and the International Geophysical Year. In the winter of 1957, Fuchs was at his base by the Weddell Sea in readiness for his journey across the continent; Hillary was at Scott Base with the first New Zealand wintering-over party preparing for the considerable programmes planned for that group.
Back in New Zealand, interest in Antarctic matters was keen. But opportunities for participation in Antarctic research programmes were few. Dr.
It was, however, known that the Ross Sea Committee, then charged with the organisation of the New Zealand T.A.E. activities, and the Royal New Zealand Navy, were planning a summer cruise of the Ross Sea for H.M.N.Z.S. Endeavour, the elderly wooden supply vessel used for New Zealand Antarctic transport.
It seemed to me that a good case existed for the Endeavour to carry on this cruise two geology students. Who knew what they might come across? It so happened that two likely-looking students were then studying Geology III—Barrie McKelvie Now Dr. B. C. McKelvey, Lecturer in Geology, University of New England, Armidale, N.S.W. Now Dr. P. N. Webb, Geologist, N.Z. Geological Survey, Lower Hutt.
Money for clothing and equipment did not exist. Application to the N.Z.U. Research Committee for £100 produced only £50. Dr. J. Williams, Principal of V.U.C., provided another £50 from College funds. Some old World War II battledress of mine, and some other odds and ends completed the equipment, and the first Victoria University Expedition was on its way south.
From this point onwards McKelvey and Webb surpassed all expectations. They fitted in excellently on board Endeavour, and impressed the helpful Commander, Capt. H. Kirkwood. At Scott Base, their attitude towards hard work won them more friends. The intended Ross Sea cruise of Endeavour did not eventuate, but through the good offices of Dr R. Balham, Zoologist of the wintering-over party, an opportunity was made for one of the pair (they tossed, and Webb won) to join a biological trio of T.A.E. heading by U.S. helicopter to what is now named (after Victoria University) Victoria Valley. The first geological mapping of this ice-free valley system was carried out by Webb, and although the party was in the field for only ten days, he accomplished a considerable amount of work.
Later, an opportunity arose (largely through Phil Smith, the U.S. Scientific Co-ordinator) for McKelvey and Webb to visit ice-free valleys in the vicinity of the upper part of the Taylor Glacier. Here, too, a great deal of unmapped territory was surveyed.
Webb and McKelvey left Antarctica in the last Globemaster to fly out, late in February, as the airstrip on the sea ice of McMurdo Sound broke up.
Their successes were such that recognition of the value of student participation in Antarctic Science was established. It is pleasing to record that the N.Z.U. Research Committee restored the cut £50.
Parts I and II of the V.U.W. Antarctic geological series were completed by the two students very quickly, and were published in 1959, among the first N.Z. geological publications of the new Antarctic area. This work won them the Hamilton Prize of the Royal Society of New Zealand.
The ice-free valleys of the McMurdo region were obviously worth further investigation, and so another expedition was planned for the following summer, 1958-59. At this time Dr. 4 Now Professor C. B. B. Bull, Director, Polar Research Institute. Ohio State University, Columbus, Ohio. Now Lecturer in Zoology, Australian National University, Canberra.
Dr. Bull, experienced in planning University expeditions in Britain, sought donations of equipment and finance from various Wellington and other business films. Response was generous, and little other finance was necessary. It was planned to carry out geological, geophysical and biological investigations and topographic surveying work in the Wright Valley, south of Victoria Valley.
It is, in retrospect, of interest to note that despite the strength of the expedition members, the lack of need for funds, and the clear importance of the scientific objectives, this expedition experienced difficulties when official approval was sought. In 1958 the Ross Sea Committee ceased executive functions and New Zealand Antarctic Research was controlled by a newly constituted Ministerial Committee, the Ross Dependency Research Committee, and from that
Initial difficulties with the University's application led to considerable argument. The problems resulting from technicalities and misunderstandings were later cleared up. To Dr. Hatherton, a good friend of the University's Antarctic ventures and a member of the Committee, we owe much for the help he gave us in overcoming obstacles which might otherwise have terminated our activities as an independent unit in New Zealand's Antarctic Research programme. Since this time, we have enjoyed the strong support of R.D.R.C. in all our activities.
The programme in the Wright Valley was successful, as study of the publications (a list is appended to this article) will show. Bull caried out a gravity survey from the coast, over the Wilson Piedmont Glacier, and up the valley towards its head. Barwick extended his biological investigations, and McKelvey and Webb made a geological survey of this large ice-free valley. Dolerite samples collected for paleomagnetic work, subsequently worked on by Bull and Irving at Canberra, produced data of importance in paleogeography.
Early in 1959, it was thought worthwhile to continue the work. It was decided to formalise planning and organisation of future Victoria University Expeditions by means of a Committee, and there was set up by the Professional Board the Antarctic Research Committee. Its members were C. B. B. Bull. R. Barwick and
Dr. Now on Ph.D. Research at Imperial College, London. Now Dr. Now Dr. I. A. G. Willis, Petroleum Development (Oman) Ltd., Doha Qatar, Arabian Gulf.
(It may be remarked in passing that attempts were made, without success, to include a woman member in this expedition. The girl concerned, a sound field worker, was very keen to go).
The expedition was in the field from November to early February. Again, all objectives were achieved. It is pleasant to record that, as with the previous expedition, substantial contributions to the venture came from business firms as well as from official sources.
Plans for the next season's activities advanced rapidly during the early part of 1960. Ralph Wheeler was appointed leader of the next expedition, which was scheduled to examine and map the geology of the Koettlitz ice-free margin. This extensive area, about the size of the Wairarapa Valley, almost entirely free of ice, had appeared ideal for a University expedition when reconnoitred from the air by the writer early the previous season.
Other members of this party were Ian Willis, Roger Cooper Now Ph.D. student, Victoria University. Dr. H. R. Blank, U.S.G.S., Menlo Park, California.
Ralph Wheeler referred to his party, for convenience, as “VUWAE” (V.U.W. Antarctic Expedition). The term was useful, and as this was the fourth expedition it became known as VUWAE 4, the earlier parties then being numbered appropriately for reference.
Publications of the results of VUWAE 4, when added to the published work of VUWAEs 1, 2 and 3, largely completed reconnaissance geological mapping of the large (2,000 sq. miles) ice-free area between the Koettlitz and Mackay Glaciers. Only the lower Taylor had not been covered by V.U.W. parties.
The following winter, the V.U.W. Antarctic Research Committee took up a suggestion by Dr. Bull, by that time at Ohio State University. This proposal involved a break with the by now traditional largely student geological surveying teams, as it involved a highly specialised problem. On VUWAE 2. Dr. Bull and his party had seen and named Lake Vanda in the Wright Valley. Vanda has a 12 ft. ice cover; with no ice drill, Bull had been unable to penetrate this cover but he noted the lake looked “odd”, and had estimated its depth from his gravity results. He recommended it to some Americans in search of algae; they drilled the ice cover and found their algae. They also found the bottom waters were saline and warm, and concluded that the heat was of geothermal origin.
We decided Dr. Bull's suggestion, that a VUWAE also study the lake, was a good one, and so VUWAE 5 went south. The personnel were both senior staff members, Drs. Now Associate Professor of Geology, V.U.W. Now Associate Professor of Chemistry, V.U.W.
After this specialised venture, it was thought by the Committee that opportunity existed for a further expedition of the earlier type. So for the summer of 1962-63 we planned VUWAE 6, for the Brown Hills and Darwin Mountains areas, about 200 miles south of the Koettlitz, reconnoitred from the air by Ralph Wheeler and the writer the previous summer and judged suitable for student work.
An innovation was the appointment of a student as leader—Ian Willis, by now an M.Sc. student and veteran of VUWAEs 3
Now Demonstrator in Geology, University of Queensland. Now at N.Z. Geological Survey. Now Dr. J. Now in Department of Agriculture, Palmerston North. Now Professor C. C. Rich, Bowling Green State University.
After mapping the Brown Hills—a fairly limited area—the expedition crossed the Darwin Glacier to the Darwin Mountains. Crevasse conditions were such that the party crossed in a U.S.N. R.4D aircraft. Following work in the Darwins, the party returned to Scott Base with some time still in hand. This time they spent very profitably in the Taylor Valley, thus completing the geological survey of McMurdo Oasis begun by McKelvey and Webb five years previously.
VUWAE 6 was, however, not the only Victoria University expedition of the 1962/63 summer. The work of Wellman and Wilson on Lake Vanda had been of interest to New Zealand physicist, both at V.U.W. and D.S.I.R. Other Lakes in the Taylor Valley appeared of interest, and so a small three-man party, led by T. Shirtcliffe of the Physics Department, V.U.W., and including R. F. Benseman of D.S.I.R. and Bruce Popplewell K. B. Popplewell, Patents Office, Justice Department.
By the autumn of 1963 evaluation of data from Lakes Vanda and Bonney had progressed to a stage when it was apparent that further work on these and other lakes was of prime importance. Accordingly VUWAE 8 was planned for this end.
W. Prebble, a veteran of VUWAE 6, was appointed Leader. The expedition operated in two phases—for the first phase, mainly in the Taylor Valley, Professor Now Dr. R. A. Henderson, Geology Department, Harvard University. Now Dr. D.
Lakes studied included Fryxell, Chad, Bonney, Hoare, House and Joyce in the Taylor Valley; Vanda, Canopus and Don Juan in the Wright Valley; and Webb, Vashka and Vida in the Victoria Valley system. In addition, some geological observations were made and a reconnaissance flown to examine White and Black Islands and Brown Peninsula with a view to a future expedition.
Wilson and House spent a week at South Pole Station studying chemical composition of polar snow to ascertain how much atmospheric nitrogen was fixed by auroral activity, and also to examine micrometeorite content of the ice-cap.
Planning of VUWAE 9, for the following summer, presented some problems. The reconnaissance by members of VUWAE 8 suggested that a period of several weeks could be spent with profit on Black and White Islands south of Scott Base, and on Brown Peninsula. It was clear that the studies should be multi-disciplinary, and, further, would not involve a whole season. Certain other problems, including the question of possible mineralisation in the Koettlitz area, could be tackled by the expedition. Accordingly a complex and highly specialised expedition was assembled. Warwick Prebble, now an M.Sc. student, was again appointed Leader, and two other research students became members for the entire season. They were Now Ph.D. student at Physics Department, Oxford University.
For phase I, the period on the islands and peninsula, scientific leader was Dr. Now Associate Professor of Geology, V.U.W. Now Dr. J. Cole, Lecturer in Geology, V.U.W.
During phase II, Professor J. Bradley was scientific leader, and members were Dr. D. Zimmerman, of the University of Auckland (economic geologist), Fred Schafer (Technician), and Don Palmer Now at Geology Department, Princeton University.
Some very interesting results emerged from the work of this expedition, both on Quaternary history of the Ross Sea area and on petrological details of basement rocks of the dry valleys.
Like its predecessors, this expedition achieved its objectives, numerous and complex as these were.
The work of all VUWAE personnel has been creditable but special mention might be made here of Warwick Prebble. This had been his third successive summer in Antarctica and his second as Expedition Leader. Leadership of expeditions which included as members persons such as those listed above was no small task for a research student. Much credit must go to Prebble for the success, smoothness and safety of the operations of VUWAEs 8 and 9.
When the V.U.W. Antarctic Research Committee (now consisting of
One such had been Inexpressible Island, well north of the Dry Valleys, and, with nearby ice-free areas, presenting a well exposed but small region of the basement. Dr. Ed Ghent Now Professor E. Ghent, Geology Department, University of Calgary. Demonstrator in Geology, V.U.W. Now at B.M.R., Rabaul.
Owing to transport problems, VUWAE 10 never reached Inexpressible Island. Hence the secondary objectives became primary, and petrological studies were undertaken in the Taylor Valley near Lake Bonney and Mt. Falconer, and in Victoria Valley, with collections of specimens for refined laboratory analyses which are still proceeding.
VUWAE 11, in the summer of 1966/67, consisted of three distinct groups, with quite different objectives. Professor Wellman, Leader, and Andrew Duncan were concerned with current geological processes operating in the Wright Valley, especially the role of salts. Ian Smith and Vince Neall undertook petrological and structural work on Nussbaum Riegel, Taylor Valley. The third group, a geophysics team comprising Dr. D. A. Christoffel and Ian Calhaem, carried out heat flow measurements in McMurdo Sound.
At the time of writing, July 1967, VUWAE 12 is planned for next summer. Three small, detached parties will carry out widely different specialised tasks, geological, geochemical and geophysical.
The character of Victoria University Antarctic work has changed, and is still changing. Personally I regret the passing of basic geological mapping by teams, mainly students, operating in the ice-free areas. VUWAEs 1, 2, 3, 4 and 6 were of this type. Good scientific returns and excellent experience for all participants resulted from this type of expedition.
Unfortunately ice-free areas are limited, and none of reasonable size remain to be covered in the Ross Dependency. Beginning with VUWAE 5, specialisation developed. VUWAEs 7 and 8 were highly specialised limnological expeditions; VUWAE 10 specialised in detailed petrology. The results of these have been well worth while, but they did not provide quite as much scope for individual student initiative and variety of experience as the earlier parties.
We are now tending towards fragmentation as well as specialisation. The main aims of VUWAEs 9 and 12, and to a lesser extent VUWAE 11, exemplify this tendency. This, too, is inevitable—there are many promising trails. Pressures of very widely differing interests are involved in our work, but there are few in each group. Hence it follows that our best use of our scientific resources at the present time involves us in divergence in specialised aspects of Antarctic Science.
Many persons and organisations have aided and encouraged our efforts. Without the logistic support of the R.N.Z.N., the U.S.N. (VX 6) and the U.S.A.F., the work could not have been done. We have received funds from many sources—the U.G.C. Research Committee, and its predecessor, the U.N.Z. Research Committee; the Council of V.U.W. (formerly V.U.C.); from D.S.I.R.; from N.S.F. of the United States; from the
Other V.U.W. groups which have operated in Antaretica include the following:—
1959 Reconnaissance of Mackay and Koettlitz Glacier areas —
1961 Reconnaissance of Brown Hills/Darwin Glacier area —
1962 Work on Ross Island —
Now at the Volcanological Observatory, Rabaul, New Guinea.
Antarctica is perhaps the most stable of the continents. Some earthquakes occur in shield areas such as Australia and North America, but the only major shocks recorded from Antarctica originate from outside the Antarctic Circle. This lack of earthquakes is, perhaps, only a feature of the present, but it is distinct. Antarctica has, however, undergone great past tectonic upheavals which have given rise to complexly folded strata, and to mountains which now rise to heights of the order of 15,000 feet above sea level.
Antarctica can be divided into two provinces, eastern and western Antarctica, each with their characteristic physiography and geology. The western province includes the Antarctic Peninsula, Marie Byrd Land, and the western coast of the Weddell Sea. It is geologically related to the fold mountain chains of the Andes and New Zealand. The eastern Antarctic geological province includes most of the remainder of the continent (Map 1) and is related to the African, Indian and Australian shields. Little is known about the transitional zone which separates these two provinces, and extends from the Ross to the Weddell Sea.
The eastern Antarctic province resembles a number of other ancient and highly stable landmasses, which are thought to have once been parts of a single continent — Gondwanaland. South Africa, India, Australia, parts of South America and eastern Antarctica, all have broadly similar geology, especially in respect of the Devonian to Jurassic rocks. These resemblances have supported the idea that a single southern continental mass was broken apart at some time in the late Mesozoic and the pieces have since drifted into the positions they now occupy.
Antarctica is a continent which is almost completely covered by a vast ice cap. Around the margins of the ice cap the peaks of the coastal mountains protrude to form nunataks, while further toward the sea the ice cap is split by the mountains into numerous glaciers which descend through steep sided valleys to the coast. Geology in such a country is thus a study of fragments of observations on isolated nunataks and steep sided valley walls, with many inferred
The McMurdo Oasis, an ice-free valley system covering 2,500km2, lies about 100 miles to the north-west of Scott Base and is bounded by the Polar Plateau to the west, and the Wilson Piedmont Glacier to the east. Three major valleys extend from Lat. 77°10'S to Lat. 77°45'S. The central, deep, Wright Valley has an altitude not greater than 1,200 ft, yet is bordered on both sides by mountains rising to 6,000 ft. To the north lies the Victoria Valley with Lakes Vida and Vashka, and to the south, the Taylor Valley, in which are situated Lakes Bonney and Fryxell.
The rocks in these ‘Dry Valleys’ can be divided into two broad categories, a basement complex and a younger overlying sequence of rocks. The former has a complex history of folding, metamorphism and intrusion, while the latter is of simple structure and has suffered little disorder since formation. The approach adopted in this article is to present the geology of the Dry Valleys as a series of events which over a great period of time have built up the geology as seen today.
All of the rocks which are older than Lower Devonian can be conveniently grouped under the heading, basement rocks. The oldest rocks are marbles, schists and gneisses, originally laid down as impure limestones, mudstones and greywackes, in a Precambrian geosyncline which lay where the Victoria Land coastline now exists. Deposition of sediments in this geosyncline is inferred to have taken place more or less continuously during the late Precambrian and Cambrian. The Cambrian fossil Archaeocyathus (or a closely allied genus) has been found in correlated rocks outside the Dry Valley region. These metamorphosed sediments are called the Skelton Group of Metasediments and in the Wright and Victoria Valleys they have been named the Asgard Formation of the Skelton Group.
The Skelton Group was injected by coarse grained gneisses and metadiorites and then folded in an orogeny which probably occurred in Ordovician times. The pretectonic intrusives are, accordingly, deformed to a degree comparable to that of the marble in the
A third post-tectonic period of intrusion occurred between the Ordovician Orogeny and Devonian times. Large quantities of granite were intruded and these are reported to be sheet-like and to lie on top of the earlier basement rocks. This posttectonic
A period of erosion of unknown length followed this phase in the McMurdo Oasis. During the erosional period a peneplain was formed with a relief in the order of a few hundred feet. It is called the Kukri Peneplain after the Kukri Hills in which it was first recognised. The Kukri Peneplain marks the boundary between the basement rocks and the overlying, near horizontal sediments described below. These sediments, at least Devonian in age, date the development of the Kukri Peneplain as pre-Lower Devonian.
From Devonian times until Late Triassic times there was a period of slow sedimentation during which a thick series of continental type sediments were deposited. They include siltstones, sandstones, shales, arkoses and a pebble subgreywacke, overlain by at least 2,500 ft of well sorted, massive and cross-bedded quartzites. Interbedded thin coal seams are common in the upper parts of the sequence. Sedimentary structures in the rocks include graded bedding, cross laminations, cross-bedding, ripple marks, dessication cracks and concretions. Upper Permian plant spores and various ‘fossil problematica’ such as worm casts and the tracks of invertebrates have been found within these sediments. In areas adjacent to the Dry Valleys, freshwater placoderm fish fossils, Devonian in age, and plants typical of the Upper Paleozoic Glossopteris floral assemblage, have been found. The Devonian to Triassic sedimentary sequence is termed the Beacon Group. It was probably slowly deposited in shallow seas, estuaries and lakes from a granitic terrain similar to that which forms the basement complex in the Dry Valleys at present.
During Jurassic times there was a further period of igneous intrusion during which thick extensive dolerite sills were emplaced in the basement rocks and Beacon Group. Three main horizons were intruded:
1. within the post-tectonic granite,
2. along the Kukri Peneplain Surface,
and 3. in the lower parts of the Beacon Group.
The first two horizons were each intruded by a single sill, while the upper horizon was intruded by a number of sills. The two lower ones are between 900 and 1,300 ft thick. The uppermost sills, within the Beacon Group, were intruded as horizontal sheets roughly parallel to the bedding of the sediments. They are thinner and less regular than the lower sills and tend to bifurcate and pass via steeply dipping dykes, from one level to another. The whole sequence of dolerite sills and dykes is called the Ferrar Dolerite Formation after H. T. Ferrar, the geologist to Scott's Antarctic Expedition of 1901.
A possible Tertiary deposit exists at Marble Point, but no sediments have yet been definitely recorded in the McMurdo Oasis between Upper Mesozoic and Quaternary times. The Quaternary geological history of the area is represented by a series of moraines deposited by glaciers, and by basaltic volcanics and a series of raised beaches along the coast.
The McMurdo Volcanics occur as numerous small scoria cones and lava flows typically on the upper slopes of the valleys. They are common in the Taylor Valley and in the area at the foot of the Royal Society Range, but are not present in the Wright and Victoria Valleys. These volcanics are a part of the episode which gave rise to the large volcanoes of Erebus, Terra Nova and Terror, which make up Ross Island, and to Mt. Discovery with the line of recent volcanoes extending northwards along the Victoria Land coast.
The moraines are a product of Quarternary and Recent fluctuations of the Polar Ice Cap, the Ross Ice Shelf and local névés. In areas to the south of the Dry Valleys, moraine loops cross the valley floors in large numbers. In the McMurdo Oasis the separate moraines are distinct, some younger and others older than the scoria cones and lava flows of the McMurdo Volcanics.
The most important event of recent times was the Victoria Orogeny during which the gross features of present day Victoria Land were formed. This orogeny was characterised by block faulting with considerable vertical uplift, but there was negligible folding of the Beacon sediments, which together with the Dolerite sills now dip at about 7° towards the west.
Beach deposits are widespread throughout the Ross Dependency, and may be found at the entrance of the Taylor Valley, and, on numerous islands to the north. It has been estimated that the oldest raised beach is 5,000 years old.
Figure 4 illustrates the Dry Valley geology as seen today, with the basement rocks exposed at the coast and the dolerites and Beacon sediments occurring in the upper levels of the valleys towards the Polar Plateau.
Meteorological data from this region are scarce, and only a few summer records have been obtained by Victoria University Antarctic Expeditions. While in the Taylor Valley, the authors noted the predominant easterly wind direction recorded by Bull in the Wright Valley. For 25 days at Nussbaum Riegel, Taylor Valley, in December, 1966, westerly wind was recorded on only six occasions. The mean annual precipitation is probably within the range 10 inches to less than 1 inch water equivalents. Snowfalls do occur in summer, for between 8th-10th December, 1966, at Nussbaum Riegel (height 2,100 ft), four inches of snow were recorded. Even at Lake Fryxell (125 ft ASL.) snow was observed. However, this snow is particularly light and ‘dry’, and on melting yields little water. The snow very quickly ablates or melts into the moraine. Permafrost levels varied from depths of 12 inches, in moraine, to 4-5 ft in loess deposits.
The origin of the McMurdo Oasis, has been long debated. The only satisfactory theory yet proposed, is that of McKelvey and Webb, who suggested that there was a decrease in Plateau ice, resulting in a reduced ice flowage through the valleys. Wilson calculated from lake studies that the minimum age glaciers ceased flowing through the valleys was about 50,000 years ago. It should be emphasised that the present arid climate is not a cause of deglaciation.
At Scott Base the snowline is at sea-level, but suddenly to the west, in the McMurdo Oasis, it rises to 7,000 ft. Beneath the snowline, conditions are cold but dry, and it is surprising to find that the central Wright Valley with an annual rainfall of probably less than 10 inches, is one of the driest places in the world. Although the origin of the valleys is undoubtedly a result of glacial action, the present climate has grossly modified the features now exposed. The cold, dry climate affects the weathering processes, and erosional features of temperate climates are absent. (see Fig. 5).
An interesting feature found throughout the Dry Valleys is that of salt weathering. Salt accumulations may be found below the surface of the soil, on bare rock surfaces and even on the adjacent sea-ice of McMurdo Sound. Salt solutions predominantly of nitrates, chlorides and calcite, carried inland from the sea, penetrate minute cracks, and on crystallizing rend the rocks apart. Salt
From December to the beginning of February, meltwaters from the glaciers begin to flow as small streams. In small depressions of the valley floors the meltwaters accumulate to form lakes, the surfaces of which are frozen in winter. In late spring they melt around the perimeters and by mid-summer a 50 ft wide meltwater rim may be present. The River Onyx, in the Wright Valley, is one of the largest rivers flowing 18 miles inland to Lake Vanda (410 ft ASL.). Smaller streams flow into the other lakes, and at Lake Bonney one stream has carved an 8 ft deep channel in the moraine. However, in relation to other processes, water erosion is negligible. For the rest of the year, the dominant transporting agent is wind. High velocity, katabatic winds descend from the higher Polar Plateau through these valleys to the coast. Sand grains are blown across the valley floors modifying fractured dolerite blocks to a ventifact appearance so typical of the desert regions of the world. These blocks vary in size from a few inches to greater than 7 ft in diameter. Sand-dunes have accumulated in exposed areas, and drifting barchans are a feature in the Victoria Valley. Most of the valley floors are covered in moraine derived from Polar Plateau and local glaciers. On steeper slopes, coarse scree debris accumulates on top of the bedrock. An unusual but effective method of boulder movement downslope, apart from rolling, appears to be by sliding of rocks over snow patches.
In the valley bottoms the graves and sands are frozen solid with ice to a great depth. In winter the intense cold causes the ground to contract to form shrinkage cracks 10 - 20 ft across. The resultant polygonal pattern which is found in most low lying areas is highly characteristic of this region.
The authors wish to thank Professor J. Bradley for assistance in the preparation of this paper.
(See appended VUWAE List on Page 114.)
Between 1961 And 1966 Canterbury University Antarctic Biology Unit undertook research on Adelie and Emperor penguins ( Pygoscelis adeliae and
The unit began work at a small colony of Adelie penguins at Cape Royds (Ross Island) in October 1961. We originally intended to use the colony for experimental studies of behaviour, nesting success and microclimate, following earlier work in the 1959-60 season by Taylor (1962). This programme was abandoned when counts of nesting birds showed that the colony had declined seriously since 1956; instead we began a study of the breeding population, recruiting rates, and ecology of the colony, involving as little interference as possible. Birds banded by Taylor and others formed a valuable nucleus of known experienced breeders, and additional birds were banded each season to maintain a marked population of useful size.
The five seasons’ observations showed that the existence and continuing success of the colony (the southernmost in the world) depends on the annual formation of a polynya, or pool of ice-free water, in the sea ice close to Cape Royds from October onward (Stonehouse 1967b). Strong currents meeting off the Cape have been known to keep this area of the Sound open even in midwinter, when surrounding sea ice is 8-10ft thick. In November and December the polynya allows Cape Royds penguins to feed within a few miles of the colony during spells of relief from incubation and in the early stages of chick rearing, while the rest of McMurdo Sound is still ice-covered. A similar relation between polynyas and isolated high-latitude colonies has been noted elsewhere in Antarctica (Stonehouse 1964a, 1967b).
Adelies starve during courtship, living entirely on reserves of fat. In normal years at Cape Royds courtship takes about 11 days, and males continue fasting during the subsequent first incubation watch, which lasts 8-10 days in years when the polynya is present, but extends to two or three weeks when the ice remains firm. During courtship and incubation in warmer areas male Adelies expend energy at rates averaging some 20-25% higher than the theoretical
The area of ice-free water may determine the amount of food normally available and so control the maximum size of the colony. Numbers appear to have remained approximately constant at about 1500-2000 pairs between 1907 and 1956 (Taylor 1962), in spite of losses of eggs and adults during Shackleton's two expeditions in 1907 and 1916. A large U.S. permanent expedition base was established 17 miles from the colony in 1956, and from then numbers appear to have declined, at a mean total rate of 6%, to a total of just over 1000 pairs in 1962 and 1963. Strong circumstantial evidence suggests that the decline was due to disturbances by visitors, especially low-flying helicopters which landed — often several times daily during the breeding season — on a frozen lake less than 100 yards from the colony. The position was reported to the New Zealand Government in 1962, and in 1963 the U.S. Naval authorities invited our co-operation in drawing up regulations to protect the colony. The number of visits and visitors was drastically reduced, and in 1964 a slight increase of numbers of breeding birds was noted after the long decline.
Preliminary analysis of the five seasons’ counts suggests that the decline in breeding population was due to partial failure in recruiting rather than reduced nesting or breeding success. Disturbance is believed to have affected young birds, which visit the colony as non-breeders in December and January, and may be driven elsewhere by crowding or other conditions which inhibit territory holding.
Banded birds gave insight into colony organisation. Males returning at the start of a season usually headed for a particular site, some 80% returning to sites where they were known to have bred before. Females were less determinate, usually wandering in the colonies and attaching to particular males (often a former mate) rather than sites of previous breeding. Males tended to return before their mates, spending on average nearly four days longer on the colony before the eggs appeared. About one third of the birds
Toward the end of November numbers on a colony stabilize and bear a simple relation to the peak number of nests. Aerial photographs taken at this time of the year can thus be interpreted to give a reasonable estimate of colony size, allowing rapid counts to be made in outlying colonies which cannot readily be visited on the ground. This technique has been used to count Adelie colonies at Cape Bird, Beaufort Island, Franklin Island and Inexpressible Island in successive years during the study period (Stonehouse 1966). Flights especially arranged for this purpose by the U.S. Navy have also revealed colonies of Emperor penguins at Beaufort and Franklin Islands, and allowed us to estimate their size and success. (Stonehouse 1965 and in press).
Special helicopter flights were made each year, as closely as possible to the end of November, to count Emperor penguins at the historic Cape Crozier colony. Emperors lay a single egg, incubating on their feet through winter and early spring, and carrying their chicks in the same brood cavity. By October the chicks are too large to be carried, and form creches on the sea ice close to the cliffs of the Ross Ice Shelf. By late November they are sturdy enough to be shepherded and counted. Census taken each year since 1961 have shown that the colony now has a breeding strength of about 1500 pairs, i.e. between four and five times as many as were recorded during Scott's expeditions of 1902 and 1911. The difference is due to changes in the face of the Ross Barrier; during the early years of the century the colony formed in an enclave facing the open sea, but for the past few years has assembled in deep V-shaped rifts behind the main Barrier cliff. Where previously the northerly swells of winter exposed the breeding birds to constant hazard, they are now protected from the danger of being washed or carried away until the ice breaks out in late December or January (Stonehouse 1964).
Some aspects of relations between Adelie penguins and McCormick skuas (Catheracta maccormicki) at Cape Royds were studied by Spellerberg (1967 and in press) as part of a general ecological account of the McMurdo Sound skua population.
I thank Professor
This Paper discusses current work on the population dynamics of the Weddell seal (Leptonychotes weddelli) in McMurdo Sound, Antarctica, and points out the suitability of this species for other studies.
The Weddell seal occurs in large numbers, is not normally dangerous, is unafraid of humans and thus easy to approach for observation at close range, and is easy to catch for detailed examination, measurements, or marking. No other seal offers all these advantageous characteristics.
The first work on Weddell seals by Canterbury University was originated to assess the effect of killing seals each year to feed the dogs at Scott Base. The official policy was to kill only males, but a number of femals were killed also. From 1957 to the present, at least 1,000 seals have been removed from the population.
The object of this study is to define the population parameters and movements of the Weddell seal in McMurdo Sound, i.e. the birth rate, longevity, life expectancy of age classes, pregnancy rate, dispersal, and daily and seasonal movements. This work is of value because of interest in the harvest of seals throughout the world. There has already been one Norwegian expedition to the Weddell Sea to harvest crabeater seals. It is possible that interest in harvesting the Weddell seal for pelts and blubber may grow in the future. Thus it is important to assess the population characteristics of the Weddell seal while it is still relatively undisturbed. Information gathered on this species may usefully be applied to other seals and to mammals generally.
This study follows a four year study of the Weddell seal in McMurdo Sound by Dr. M. S. R. Smith. His primary research elucidated in detail the physiology of the male and female reproductive cycle. Besides this, Smith did population counts and recorded daily and seasonal movements during the period 1961-1965, studied the louse Antarctophthirius ogmorhini on the Weddell seal (Murray et al., 1965), assimilated data on injuries to the Weddell seal (Smith, 1966b), and recorded detailed body measurements and organ weights.
A general parasite study with special consideration of the bile duct cestode Glandiocephalus perfoliatus was done by D. W. Featherston (1965).
From 1963-65 branding of seal pups was carried out under the direction of Dr. Bernard Stonehouse. Autopsies were made on seals killed each year for dog food, and over 260 skulls with canine teeth were collected for the development of aging techniques. This work is in progress at present.
In addition, Dr. R. Balham of Victoria University, Wellington, and Dr G. L. Kooyman, formerly of the University of Arizona, have given free access to the data they collected on Weddell seals in McMurdo Sound during 1957 and 1963-1965 respectively.
The combination of these sources provides an excellent background of reference material for the present ovservations.
Weddell seals in McMurdo Sound pup on the sea ice from the middle of October to early November. They weigh about 65 Ib. at birth (Bertram, 1940), double their weight in 10 days, and are
Females first become pregnant at three years of age and have one pup a year thereafter. One female was found pupping in her third year, thus having bred in its second year, but this is exceptional (Smith, 1966a). Twinning is virtually non-existent. Weddell seals may live to 15 or 16 years of age but the average age in McMurdo Sound is about eight years.
There is a resident winter population of Weddell seals in McMurdo Sound (Wilson, 1907) estimated to number about 250 (Smith, 1965). These seals live in the water during the winter and maintain air holes by gnawing the ice with their teeth. Most of the McMurdo Sound population returns in two waves; the first in early October consisting mainly of breeding females, and the second in December and January consisting of adult and sub-adult males and females. The maximum combined adult and sub-adult population is approximately 2,500 in mid-January and begins to decline again by the end of February (Smith, 1965). It has been suggested that the seals which leave McMurdo during the winter also go to the pack ice and inaccessible northern coast (Smith, 1966a).
Of primary importance in a population study of this sort is the marking of individual animals. On a short term basis this gives information on daily and seasonal movements while on a long term it provides information on dispersal, survival, and fidelity to breeding sites. Data are gathered by continuously checking for tagged seals throughout the season.
Initially the marking programme was concerned with the identification of year classes. Thus, pups were branded in three consecutive seasons with a brand to designate the year. In 1963, 85 pups were branded with the letters VL, in 1964, 280 pups with the letters IV, and in 1965, 90 pups with the letter ZX and 250 with the letter H. (Smith, 1966a). During 1963 through 1965, 604 seals (including pups, sub-adults, and adults) were tagged by Kooyman with numbered monel-metal tags.
During the initiation of my phase of this study in January through February, 1966, I tagged 252 Weddell seals in McMurdo Sound (including six at White Island) (Stirling, 1966a and b). These
To understand what is happening in a population it is essential to determine how discrete it is. The study area here is defined as the west coast of Ross Island between Cape Royds and Scott Base, including the Delbridge Islands (Figure 1). To check on the movements of individuals in or out of this area, trips were taken to other locations to look for tagged seals from the study area, and to tag seals to see if they move into the study area. The following list summarizes the places visited and the number of seals tagged at each location in 1966-1967. Figures 1 and 2 show the location of these sites.
The coast of Victoria Land and associated pack ice between McMurdo and Cape Hallett were examined for the presence of seals through the aid of U.S. Coast Guard Cutters “Staten Island” and “Glacier”. Two types of observations were made. The first was a census by helicopter over five sites along the coast; Cape Roberts, Nordenskjold Ice Tongue, Prior Island, Inexpressible Island, and Borchgrevink Glacier Tongue (Fig. 2). At one concentration of seals at Cape Roberts and again at Nordenskjold Ice Tongue, we were allowed onto the ice to look for tagged seals and obtain the approximate age and sex ratios of seals present. The second type of observation was a quantitative count from the bridge of the icebreaker of the numbers of each seal species seen in the pack ice.
Through the season aerial census of the study area was done by helicopter to follow the build up of total numbers of seals and seasonal population shifts.
To calculate the survival and productivity of a population it is necessary to obtain data on the age structure and reproductive status of the population. This is facilitated by the collection of canine teeth (from which individuals can be aged) and reproductive organs from seals killed for dog food at Scott Base.
Sixty-eight percent of the seals tagged in January and February, 1965, were re-sighted in the next season. This is an excellent
Most breeding females originally tagged by Kooyman and resighted this season with pups, were breeding at the same place. This suggests fidelity to a pupping site.
The southward movement of the population as described by Smith (1965) was confirmed in this study by sighting of tagged individuals. Total numbers appear to be similar to past seasons. In the influx of seals in December through January many tagged seals were sighted that had not previously been seen in the pupping areas. This raises the possibility of seals breeding in other areas or the presence of a substantial proportion of non breeders and unsuccessful breeders.
Very little movement of tagged seals out of the study area during the breeding season was recorded. Five records were made outside the study area. Three were sub-adults, one was a pup, and one was an adult male. The adult male later returned to the study area. Seals were checked daily at Cape Bird and only one adult, one sub-adult and one pup from the study area were sighted. The remaining two sub-adults were sighted at Marble Point and Cape Crozier. No seals tagged in other localities were seen in the study area.
The concentrations of seals along the Victoria Land Coast appeared to be normal breeding populations similar to that in the study area. Large numbers of sub-adult seals were not seen in either the fast ice or the pack ice. Several Weddell seals were seen in the pack but only one was distinguished as a sub-adult.
The killing of seals for dog food is done in February. The population is mainly adult with some sub-adults and occasional pups. The age span and mean ages of seals killed in 1966 and 1967 are as follows:
Smith (1966a) determined pregnancy by the presence of extraembryonic membranes, but because the embryo does not implant for two to three months after mating (i.e. it
It is too early at this stage to draw conclusions further than the information given in the results. The purpose of the paper was only to describe the current work being done.
The Weddell seal is obviously suitable, because of its placid nature and availability, for detailed work in a variety of subjects such as population dynamics, metabolic rate, heat conservation, and underwater acoustics. It has, for example, been suggested that the Weddell seal has a sort of biological sonar similar to that of dolphins, which is used to find air holes and possibly fish during the continuous darkness of the Antarctic winter (Ray, 1965). Yet no experimental work has been done to date.
I am grateful to Dr. Bernard Stonehouse for advice and discussion of problems arising from this study. I am also extremely appreciative of the support and co-operation of the following: the Zoology Department, Canterbury University; the Antarctic Division of the D.S.I.R. (Wellington); the University Grants Committee (Wellington); the U.S. Navy Squadron VX-6, and the U.S. Coast Guard Cutters “Staten Island” and “Glacier”
Some individuals deserve special mention. R. East was my assistant for the 1966-1967 season. J. T. Darby and A. J. Peterson tagged seals at Cape Bird and made a daily check for tagged individuals. C. M. Clark, leader of Scott Base 1966-1967, gave support without which much of this work would have been impossible. The following Scott Base personnel assisted with field work: W. Orchiston, R. G. Rae, A. C. Rayment, and A. J. Simm.
Studies On The Skua by members of the University of Canterbury have been at two of the major concentrations of skuas on Ross Island, at Cape Royds, occupied each year from 1959 until the summer 1965/66, and at Cape Bird for the past two summers. The study shifted to Bird to allow examination of a larger, more typical, grouping of skuas about penguins than at Royds.
The South Polar Skua ( Catharacta maccormicki) is similar in size and appearance to the juvenile of the largest of the New Zealand gulls (
These birds spend most of the year away from the Antarctic, and although few have been seen at this time it has been suggested (a) that they live in the pack-ice zone ringing the continent and/or (b) tour the main oceans of the world, even beyond the equator. Studies on skua at the moment all have a common starting point with the return of the first birds in spring. These appear at Ross Island in late October but take little interest in their breeding areas until about the second week in November. The Ross Island birds seem now to gather first at the McMurdo-Scott rubbish dumps and disperse later. The birds nest singly or in loose colonies around the entire continent wherever there is ice-free land near the sea, both with and away from breeding penguins. A few nest far inland where they seem to be existing on food taken from breeding petrels.
Some 600-700 pairs of skua breed on the western side of Ross Island. Roughly, there are three breeding areas: on the Dellbridge Islands and Cape Evans, about Cape Royds, from Cape Barne in the south to Rocky Point in the north, and a single very large group much further north about the Cape Bird rookeries (Cape Bird itself is five miles further north again and is ice-covered). The only other major breeding area on the island is at Cape Crozier, forty miles to the east. Spellerberg (1966) found fewer breeding birds on the western side of McMurdo Sound during a recent survey there. The skuas in three of these areas have been studied in some detail recently; those at Royds by Young in 1959/60 and Spellerberg in 1963-1965, those at Bird by Young in 1965/66 and Young and Procter in 1966/67 and those at Cape Crozier for a number of years by Robert Wood for the Johns Hopkins University. [In case this seems a lot of people for one bird, I mention that there is also a vigorous programme at Cape Hallett operated by the New Zealand D.S.I.R., and at least two other studies by other countries elsewhere in the Antarctic.]
The University's programme has gone through a common enough evolution, starting with the general study of nearly all aspects of the breeding biology and maturing into more detailed work on single topics. These are considered below.
Begun by Young at Royds and Reid at Hallet and continued by Spellerberg at Royds these involve recording the success of the various phases leading to the fledging of juveniles at the end of summer. Pairs and nests are identified, egg laying, hatching and survival recorded and chick growth followed to fledging. Spellerberg has added considerably to the earlier work by following the same pairs through several years. He has found firstly that most skuas are faithful both to their mates and breeding territories and secondly, that there are wide differences in the survival of eggs and chicks in the different years. He is at present sorting out the factors determining the survival differences but they seem mainly to be climatic, depending on the timing and severity of the storms in each year. All these studies have shown that the skuas have a very low breeding success—only about a quarter of the eggs laid produce chicks to fly from the territories at the end of summer.
Studies of nesting birds invariably generate studies of breeding behaviour, and skua studies are no exception. The most detailed work is that of Spellerberg (1966) using as a pattern, and for comparison, the work of Perdeck (1960) on the northern hemisphere
Behavioural studies involve precise descriptions of activities (preferably into a tape recorder and backed by cine filming) from long periods of alert observation on undisturbed birds. This last condition may be more difficult to realise than previously thought. Procter (1967) found that birds acting apparently normally on the first day of a watching period became steadily more distracted as the days passed and never became used to the observer. Hides will need to be rigid and unobtrusive to be accepted at all readily and even with these doubt will remain of their effect. For most studies it is necessary to decide at the outset whether ‘normal’ behaviour is what is required or whether weights, length measurements and so on are needed. From sad experience it appears that only one of these can be studied safely with any one group of birds. Disturbed nesting skua neither leave the territory nor feed each other or the chicks—accounting for the few times feeding is seen by those walking or working in skua colonies. Birds should be handled as little as possible and even banding, though necessary, causes great distress and can change a placid group into one that is nervous and violently aggressive. In this marked sensitivity to disturbance skuas differ tremendously from penguins, which as far as it is possible to tell, settle down much more quickly following the turmoil and bedlam of nest-checking. Few penguins desert their nests during routine working.
[In the past two years I have attempted to reduce disturbance of penguins by mapping the nests in the colonies and thereafter checking the nests as far as possible from the periphery. As a working policy I have handled and disturbed skuas as little as possible, by restricting banding to a single bird of a pair, by never intentionally flushing birds from their nests and by cutting out the widespread, and repetitive, measuring and weighing of eggs and chicks. I hope through these precautions that my study of the penguin - skua association is of a “normal” situation and that the birds will continue breeding in their present numbers and distribution.]
Since the earliest studies at the beginning of the century, it has been known that although skuas lay and often hatch two eggs they seldom rear two chicks. Young (1963a) sorted out that it was the older chick of the two that invariably survived (and few exceptions
Spellerberg's (1966) work has produced a most detailed account of this phenomenon in the skua. Using thermocouples, temperatures were obtained from incubating eggs through the incubation period, in which they showed a steady temperature rise with time, and in chicks and adults over a period long enough to establish the onset of temperature stability in the former (about 50 hours from hatching) and a diurnal variation in the latter. Experiments established that the feet and legs were important areas for radiation of heat from the body when the animal was active. Such radiating areas are important in birds which have the body efficiently insulated with feathers.
The early, casual, observations suggested that skua preyed exclusively on penguins, were dependent on them entirely and nested near them because of this. [These conclusions no doubt account at least in part for the poor reputation skua enjoy.] This view was challenged by Young (1963b) and has now given way largely to the view that skua are really a fish-feeding species simply taking advantage of the abundant food to be found at times on the penguin rookeries. It is, of course, much easier to establish the skuas’ independence of penguins in areas, as at Royds, where a handful of penguins is surrounded by several hundred pairs of skuas, than when the opposite occurs.
Indeed, it is not yet certain that skuas at the large rookeries at Hallet and Crozier do need to forage at sea during summer. Certainly Maher (1966) thought that the skuas fed only from the rookery at Hallet, but the studies resulting in this paper were done in 1960/61 before their nature as fishing birds was widely
It is clear from the studies at Royds and Bird that skuas are unable to find enough food at the rookery to feed them throughout the summer. Only for a short period, from late December to mid January, is food more or less abundant in the form of penguin chicks and at this time skua pairs with more than a hundred or so penguin nests in their territory are able to feed largely from them. For the remainder of the year, and especially before December and after January, pickings are very lean and virtually all pairs feed at sea on most days. Last year a long period of northerly winds packed ice into McMurdo Sound, preventing skua from fishing there, and nearly all eggs laid were deserted as the birds began starving—in pairs without penguins and those with 500 or more penguin nests to forage amongst. The incubation period is a great strain on the male bird. He has not only to take his part in incubating but also to provide all food for the two birds of the pair. Little wonder that nests were deserted when the male was away at sea for up to 20 hours at a spell instead of an hour or two.
The general observations on the association between penguins and skuas made at Royds have been taken much further during the past two summers at Cape Bird. This study area contains 26,000 pairs of penguins and 200 skua pairs near them and provides opportunity for experimentation not possible at Royds. Three aspects of the skua-penguin association have been examined. One study has been to determine precisely what effect the skuas have on penguin breeding—the number of eggs and chicks taken. This seems simple enough to determine but is complicated by the fact that the penguins cause a considerable loss themselves, through egg infertility and desertion, and mismanagement and fighting among the breeding birds. It has been possible to apportion losses on the colonies between penguins and skuas by comparing survival in colonies fenced off from skuas with those in which they have a free run. Comparisons of this sort are useful also in sorting out whether the sudden upsurge in egg and chick mortality that occurs about the time the penguin eggs are hatching results from increased interest in the penguins by the skua, chicks being better value for risk and easier to take than eggs anyway, or from disturbance to breeding birds by penguins that had lost their nests earlier returning to the colonies.
The skuas have a number of less immediate effects on penguin breeding and these form a second study. Firstly, at least in part, they are responsible both for the colonial nesting habit of penguins — few isolated penguins rear chicks — and the close synchronisation of breeding dates within a rookery. Secondly, by taking relatively more of the progeny of both the early and late breeding birds the variation among penguin chicks becomes steadily reduced through the season.
The third topic concerns the effect of the relation on the skua. In general they are much less affected by this association. They have not lost their ability to forage at sea and there is as yet no certain evidence that they are competing for areas containing penguins instead of those that are most suitable for breeding. However, pairs nesting among the penguins fared very badly and reared few chicks. Some had their nests destroyed by penguins. All of them tended to rely on penguin food rather than forage at sea so that the nest was often deserted, allowing the eggs to cool, or to be taken by other skuas, when food was obtained after a period of starvation. Skuas breed far more successfully away from penguins except when conditions are so bad that fishing is prevented.
Direct observation involving as it does long periods of boredom to mull over things has furnished two other conclusions in this vein. As skuas are so poor at killing chicks, and feeding from them, and as birds coming newly into a rookery territory are almost totally incompetent, it seems a reasonable conclusion that they are not doing what they were designed for; which presumably is feeding at sea. Also, the best way to protect penguins from skuas, short of fencing over the colonies in cherry-orchard style, is to disturb the breeding skua pairs in the rookery as little as possible. These birds keep all others away from the penguins and their requirements are far less than for a flock of non-breeders.
As a general conclusion it is fair to say that the University's studies both at Royds and Bird have been directed at specific problems in which some answers could be expected within a season or two. This contrasts with the other approach of long term banding and recording, stretching over a number of years, that has characterised the studies at Hallet or Crozier. The two sorts of project are complementary, rather than competitive, and provide different information. Most studies have been on topics peculiar to the Antarctic, thermoregulation for example, or on general problems that are more easily investigated there than elsewhere, such as the predator/prey relation, in this case of skua and penguin. The topic “Conservation” has not loomed largely in the programme even though the skua deserves sympathy because of its low breeding success (about 1/4 to 1/3 that of the penguin), its sensitivity to
This sort of work is expected to continue for at least another three or four seasons at Cape Bird: there are more problems now than answers and the situation worsens year by year.
Biologist, VUWAE 9
THE CLIMATE of southern Victoria Land, Antarctica, appears to be inimical to plant life: the mean annual temperature is low (—20°C), winds are severe, and conditions of light and moisture are unfavourable. The extremely low atmospheric humidity of the area enables a narrow mountainous strip on the west side of McMurdo Sound to remain more or less ice-free during the summer. Precipitation is very low in this “Dry Valley” area, and the small amount of snow which does fall in the summer ablates rapidly, leaving little moisture available to plants. Abnormally long periods of summer sunlight may be as unfavourable to plants as the six months of polar night.
Despite these harsh environmental conditions, numerous small lakes in the Dry Valley area support a rich vegetation of algae. The Dry Valley lakes generally have a permanent ice cover, although some partly melt during the summer; others remain completely frozen throughout the year.
Early researchers, investigating Antarctic algal collections made by the expeditions of Scott and Shackleton, were astonished at the prevalence of blue-green algae in the samples. Extensive sheets of these algae grow in and around the ponds and lakes scattered throughout the McMurdo Sound region. They consist of a substratum of filamentous blue-green algae, with a large epiphytic flora of other blue-green and green algae, and diatoms.
Apart from the species making up the attached algal sheets, a number of planktonic diatoms and blue-green algae also exist in the lakes. Very little is known about the ecology and physiology of this Antarctic freshwater phytoplankton; however, evidence from recent investigations of lakes in the McMurdo area suggests that the algae may have rather interesting distribution patterns within the lakes. This paper is a preliminary comment on the distribution of algae in two Antarctic lakes, and the associated problem of survival under poor light conditions.
Limnological teams from Victoria University began studying some of the larger Dry Valley lakes in 1961. Their subsequent
While investigating the chemical and physical characteristics of Lake Vanda (Wright Valley), Wilson and Wellman (1962) accidentally discovered free-floating blue-green algae in a strongly convecting layer some 50 ft below the surface. In 1964, I was able to confirm this discovery by finding several species of blue-green algae and diatoms between 20-100 ft in the same lake. In a study of Lake Miers (Miers Valley), I found a somewhat similar situation where planktonic algae were apparently concentrated in a narrow convecting layer at a depth of 50 ft. Live blue-green algae were also collected from an anaerobic environment on the lake floor (Baker, in press).
In lakes with thermal stratification, the restriction of phytoplankton to certain layers is not unusual. In temperate lakes the plankton is normally concentrated in the epilimnion (above the thermocline), where currents keep the plants within the photic zone. Below the thermocline, algae drop out of suspension into a layer with slow or no circulation, and sink to the lake floor. In ice-covered Lake Miers however, the phytoplankton seems to be separated from the surface by a thermocline — there is no true epilimnion. The physiological problems involved in living in a thermal and chemical gradient would naturally restrict plankton to the convecting layers of uniform composition and temperature below the thermocline. The relationship between water turbulence, cell buoyancy, and photosynthesis may be of secondary importance in this case; the small amount of light reaching the deep convecting layer may not be sufficient for significant photosythesis.
The Antarctic lakes possess thick ice covers (<22 ft), which remain permanently frozen except for a narrow summer melt-zone around the lake edge. The passage of sunlight through the ice is impeded not only by its thickness, but also by snow, layers of sand and pebbles, and the often very uneven ice surface. Preliminary studies of several lakes in Antarctica indicate that only the surface layers receive sufficient light to support photosynthesizing algae. Experiments in temperate latitudes have shown that significant photosynthesis of algae does not occur at levels where the light intensity is less than 1% of the surface insolation.
Lake Vanda, with a relatively smooth and clear 12 ft cover of ice, receives about 6% of the incident surface light directly beneath the ice layer, and the intensity of penetrating light is thereafter halved every 50 ft. Convecting layers are now known to occur near the surface of Lake Vanda (Hoare, 1966); these would enable plants to remain in the photic zone. However, it is doubtful whether algae living deep in Lake Miers, where 18 ft of ice cover absorbs 98-99%
Algae showing an ability for heterotrophic growth under unfavourable summer conditions would have the added advantage of being able to maintain populations in the lakes throughout the dark winter. Plants receiving sufficient light in the summer (as in Lake Vanda), might have a dual ability for photosynthetic and heterotrophic metabolism; in dark conditions they could assimilate dissolved organic substances resulting from the earlier photosynthetic acitivity. Those plants which live a permanently heterotrophic existence in deep water can also utilize external organic metabolites washed down from the littoral region and inflowing glacial streams during the long summer.
Several types of organic substances are known to be effective carbon and energy sources for heterotrophic metabolism. Many substrates, such as sugars, fatty acids, alcohols, and amino acids, are intermediates in the major pathways of metabolism. Heterotrophic plants living in darkness could oxidise part of the substrate and use the energy released to convert the rest into cellular material, thus overcoming the lack of radiant energy.
Some algae may carry on autotrophic metabolism in the dark by oxidizing molecular hydrogen or hydrogen sulphide, instead of water, as in normal photosynthesis. This is an adaptive process dependent on the presence of a latent hydrogenase enzyme, which is activated only under dark, anaerobic conditions, and continues only if the light intensity remains low. Blue-green algae living in a dark, anaerobic environment near the bottom of Lake Miers may metabolize in this manner.
These suggestions are based on incomplete data and must be regarded as preliminary. It is very clear that a detailed investigation of the ecology and physiology of Antarctic lake phytoplankton will be necessary before any sound attempt can be made to elucidate their means of survival under rigorous polar conditions.
ALTHOUGH much of the Antarctic continent is covered with ice and snow there are some small areas which are ice free. One of the largest of these is the McMurdo Oasis area into which Victoria University of Wellington has sent many expeditions.
The first question that might be asked is why are these areas not ice covered like the rest of the continent. To answer this question it is necessary to consider the precipitation/evaporation balance. In this cold and arid region (mean annual temperatures of McMurdo Oasis region is approximately -20°C) only a very small fraction of the snow that falls ever melts and almost all of it is lost directly by sublimation. The best way of understanding the precipitation/evaporation balance is to consider it in terms of the single parameter—nett precipitation. This is defined as being equal to the total precipitation less the total evaporation. If this value is positive for any area in this region, the land surface will be covered with ice and snow. If this value is negative (i.e. sublimation is greater than precipitation) the area will be ice free (a so called ’dry area’), that is unless ice can flow into the area from a region of positive nett precipitation. The imaginary line which divides these two regions is called the ‘snow line’ and is the point at which precipitation equals sublimation1. For a given region the nett precipitation increases as altitude is increased. As one moves from the sea inland the snow line rises; presumably because total precipitation decreases. As one descends below the snow line the environment becomes drier and drier. Parts of this area are so dry that CaCl2. 6H2O crystallizes from ice free saline ponds (e.g. Lake Don Juan). This implies that the mean relative humidity of this area is 45% R.H. Thus one could map the relative aridity of this region by drawing lines parallel to the snow line corresponding to say 80%, 70%, 60%, 50%, 40% relative humidities. These lines not only control such physical phenomena as the presence or absence of permafrost, depth to permafrost, length of time the ice in an ice cored moraine will survive, but also have important ecological consequences in this region so inhospitable to living things. An example is the growth of lichen. It is well known that fungi can only grow at relative humidities above 80%, thus lichens can only inhabit a strip between the 80% relative humidity line and the snow line.
Thus the dry areas are those areas which lie below the snow line and into which ice, from above the snow line, cannot flow.
The McMurdo Oasis Dry Valley Area consists of a number of enclosed drainage basins. The lowest part of each is occupied by a saline lake. If we consider the evaporation/precipitation balance of the entire drainage system it can be seen that the nett excess precipitation of a snow field will flow below the snow line as a glacier. If the surface area of the glacier is insufficient to balance the sublimation/precipitation budget the glacier will advance further and further below the snow line toward a situation where the total positive nett precipitation above the snow line is balanced by the total negative nett precipitation below the snow line. Usually the glacier has pushed sufficiently far below the snow line so that some summer melting takes place. In such cases for a few days during the hottest part of the summer a stream flows away from the glacier snout and feeds a lake which occupies the lowest point of that particular enclosed drainage basin, or into that rather special saline lake called the sea. The size of the lake is determined by that area needed to balance the evaporation/precipitation equation for that particular drainage area. If there is a nett precipitation increase to the area the lake levels will rise and if there is a decrease in precipitation the lake levels will fall.
The susceptibility of the lake levels to change depends on what fraction of the total evaporation of the system is accounted for by the lake surface. If this is small a very small increase in nett precipitation to the area will lead to an increase in lake area. Thus some lakes are much more susceptible to fluctuation of surface area than others. What is usually measured is lake level. This is not only a function of lake area but also depends on the shape of the depression occupied by the lake. For a flat basin like that occupied by Lake Fryxell a large increase in area can be achieved with little increase in depth, whereas in a steep U-shaped trough such as occupied by Lake Bonney, the reverse is true.
Thus these Antarctic lakes are very sensitive indicators of changes in nett precipitation and hence of glacial advances and retreats.
The above treatment is an over simplification of the situation and deals with climatic changes only in terms of nett precipitation. Let us consider the effect of temperature changes. If the nett precipitation were to remain constant but the temperature were to decrease there would be less summer melting of the glacier so that it would advance and produce a larger area for evaporation below the snow line. This means that a smaller lake area than before would be needed to balance the system and the lake levels would drop. Conversely if the climate were to warm, more of the glacier would melt and the glacier would retreat leaving less area below the snow line so that a larger lake area would be needed to
A further effect is that the retreating glacier is replaced by a stream which can contribute almost as much evaporation as the glacier it replaces. Chemical analysis of the water of the Onyx River flowing into Lake Vanda shows that the 18 mile length of the Onyx River provides as much exaporation as the whole surface of Lake Vanda (4 miles by 1 mile).
It is therefore concluded that in this area lake level fluctuations are controlled largely by fluctuations in the nett precipation.
There is abundant evidence of past changes in lake levels. This evidence takes the form of lake shore lines higher than at present and the presence of chemical concentration gradients in the lakes.
These changes in lake levels must be a record of past climatic change. The question that immediately arises is when was this climate change and what was its cause. Let us consider some examples: Lake Vanda receded from its upper levels (shown very well in Fig. 1) some 3000 years before present. This was determined by the C-14 dating of algae found in these upper levels by Professor Wellman. While Lake Vanda stood at its upper level its surface area would have been approximately twice that at present. This suggests, as will be discussed below, that the nett precipitation to the snow fields which feed Lake Vanda (i.e. the eastern end of the Wright Valley) would have been 20% to 40% greater than at present.
In most areas of the world precipitation to a given area is controlled by its position relative to the open sea. A very attractive hypothesis is that the Ross Ice Shelf was much further to the south than its present position prior to 3000 years ago. This would mean that there would have been more open sea closer to the snow fields supplying Lake Vanda. The hypothesis that the local alpine glaciers, as distinct from those fed from the polar plateau, are controlled by mean distance to the sea (i.e. the position of the Ross Ice Shelf) is further supported by evidence that the coastal regions
All the lakes that occupy the lowest part of the various enclosed drainage basins are chemically stratified and these chemical concentration gradients contain paleoclimatic information if we can understand the system sufficiently well to interpret them.
The paleoclimatic data in the lakes are particularly welcome in the Antarctic because the more usual methods of dating climatic-events, for example, carbon-14 dating, are not often applicable in this region. This is because carbonaceous remains are rarely found.
There are two ways in which the chemistry of the lakes helps us to estimate the dates of past climatic and glacial events—firstly the total amount of salt in the lake and secondly salt gradients that may be present.
Before we can understand the chemistry of the lakes we must understand the chemistry of the whole drainage system. When snow falls on to the snow fields it contains small quantities of salts, the principle cations being sodium and calcium, and the principle anion being chloride. The chemical composition of atmospheric precipitation has been the subject of much study (see for example Ref. 2 and 3). It is well established that as far as the above cations and anions are concerned, the chemical composition of rainfall (and snow fall) depends on the position of the collecting position with respect to the sea. If two areas have the same chemical composition for their atmospheric precipitation the total salt deposited will be directly proportional to the precipitation.
The snow that falls on the snow fields that feed the glaciers of the McMurdo Region contains a fraction of a part per million of inorganic salts. It can be seen that if we measure say the sodium or chloride content of the snow in the névé of a glacier and also the sodium or chloride content of the stream leaving the snout of the glacier it is a simple calculation to determine how much water has been lost from the glacier by sublimation. Such measurements indicate that only a fraction of one per cent of the water that falls as snow in névé survives to flow as a stream from the snout of the glacier.
These salts then are carried down the stream and eventually end in the lake. Since chloride is a very minor constituent of the rocks of this area and since the glaciers do almost no cutting and carry very little moraine, it is concluded that the chloride in the lakes is the result of the contraction of large quantities of snow. It is interesting in this connection to mention the effect of permafrost on the streams of the McMurdo Dry Valleys. Because of the extremely low mean annual temperature (ca.-20°C) any water that percolates into the ground immediately freezes so that the streams all flow on ice bottoms and the percolation of ground water through sediments, which the in temperature regions can contribute large quantities of soluble salts, is quite impossible.
Thus it is reasonable to conclude that the total chloride in a lake represents the total chloride which has fallen in the drainage area feeding the lake since the lake first formed. Since the lakes in this area have a permanent ice cover many feet thick, chloride can only be removed from the lake in one of two ways. Either the lake will rise until it overflows into another drainage basin (or the sea), or a large glacier can advance through the valley and push the lake contents into the sea. Thus every lake can be considered
It is difficult to imagine a situation when the precipitation was as much as twice that at present. This is because such an increase would itself lower the snow line converting part of the glacier which now has a negative nett precipitation into a region of positive nett precipitation. The glaciers would of course advance and offset this effect but the real problem is that of rising lake levels that would result. Consider Lake Vanda for example. At present for every 100 parts of water that are deposited on the snow fields less than 20% is evaporated from the lake surface. This value is deduced from determining the chemical composition of inflow waters and snow on snow fields feeding the lakes and calculating the water lost during the movement from the snow field to the lake. If the nett precipitation for the area were to double we would be faced with disposing of two hundred parts of water and the lake area would have to increase its area at least ten fold. It would have to increase much more than ten fold in fact because its surface would be much closer to the snow line and evaporation would not be efficient. It follows from this line of reasoning that any increase in precipitation by say a factor of two or more would lead to the filling of the whole valley with lake and expanded glacier and there is no evidence for these very high lake levels.
Thus some picture of past glacial events emerges. Perhaps the most startling result is that some of these lakes, for example Lake Bonney and Lake Vanda, have chloride ages in excess of 60,000 years. It has generally been assumed by most workers in the Antarctic that these areas had been extensively glaciated during the last ice age (i.e. up until about 10,000 years ago). The salt ages for some of the lakes in this area makes this appear very unlikely.
Since the salt in Lake Vanda is largely calcium chloride whose freezing point is approximately -50°C it is almost certain that any through glacier would have pushed the salts in Lake Vanda into the sea.
Since this is a very important conclusion, let us examine carefully the assumptions made in this estimate. Firstly that all the chloride did in fact come from snow melt water. The total chloride content of Lake Vanda is in excess of 1,000,000 tons. One would need an extensive salt deposit to make any significant contribution to this quantity. The salt is calcium chloride which is so deliquescent that it would be unlikely to occur as a solid and to have survived previous glaciations.
The second assumption is that the nett precipitation to this region has not averaged six times that found at present. From the argument presented above it follows that a six fold increase in the precipitation to this area would increase the surface area of Lake Vanda by thirty fold and this would overflow into the sea and lead to a reduction in the ‘salt age’. Further as will be seen below the evidence is that the last 2000 years have been on the average drier than at present.
This idea that the Antarctic was not extensively glaciated during the last Ice Age led to the development of a new theory for the Origin of the Ice Ages (4).
Turning to the problem of the origin of chemical gradients in the saline lakes of the McMurdo Oasis — an extreme example is Lake Vanda.
A brief summary of the physical chemical structure of the lake is given in Fig. 2. The top is covered by 12 feet of ice. The region 11-55 feet and 125-160 feet has a salt gradient and must be weakly density stratified. The region 55-125 feet has a uniform temperature and uniform chemical composition, and is believed, from heat transfer considerations, to be a layer of strong convection. The lower region of the lake below 160 feet is strongly density-stratified saline water which is considered, from heat flow considerations, to be non-convective. Detailed chemical analysis of the water in this region showed that it was principally a solution of calcium chloride.
It is interesting to speculate on the origin of the salt concentration gradient in the lake. The only reasonable explanation seems to be that at some period in the past the climate was such that the Onyx River did not supply appreciable water to Lake Vanda. Under these conditions the lake-level would have dropped until only a few feet of concentrated calcium chloride remained. When the climate changed, the Onyx would flow during the summer and fresh water would have flowed on top of this strong salt solution. Since that time the calcium chloride has been diffusing upwards. If such a model is assumed, it is possible to calculate the time (5) in the past when this climatic change occurred.
If it is assumed that Lake Vanda has a flat bottom and vertical sides and that at zero time all the calcium chloride is concentrated in a layer of negligible thickness on the bottom, then the concentration profile at time t is given by:
1/2 · e−h 2/4Dt
where C is the concentration of calcium at distance h from bottom after an elapsed time t; h = distance above bottom; D = diffusion coefficient of calcium chloride = 0.68 cm2/day at 10° M = total
In the calculation the initial depth before the inflow is taken as being negligible. If this had been taken as any significant depth the gradient near the bottom of the lake would have been flatter. The experimental results suggest that the lake was indeed of small depth at the time of change in climate and also that this change was relatively sharp and definite.
The heat balance of the lakes in this cold arid region also presents some interesting problems.
The lakes fall into two types:
Type I. Many of the lakes contain water on which floats a permanent ice cover ranging from 12 to 22 feet in thickness. Each summer water flows into the lakes and under the ice. This inflow water must be equal to the total evaporation from the lake surface or the level will change with time. We will call this class of lake ‘perenially ice covered lakes’ and although they are common in the McMurdo Oasis area they have apparently not been described in other parts of the world.
Type II. Ice Block Lakes. These ‘lakes’ are really solid blocks of ice with a flat top. They are frozen to the bottom. The yearly inflow water which makes up for evaporation losses flows on top of the ice and freezes in early winter.
The problems are, (1) why should some lakes be of one sort and some of another? (2) What controls the ice thickness on the lakes that are not frozen to the bottom? (3) How can liquid water survive in lakes in a region whose mean annual temperature is -20° C? To understand these problems let us first consider the perennially ice covered lakes (i.e. Type I above). Each winter ice freezes on to the bottom of the floating ice. The amount that freezes must exactly match the total ice lost by evaporation during the whole year and melting during late summer (i.e. total annual ablation). The amount that freezes is determined by the winter temperatures, the thermal conductivity of the ice and the ice thickness. It therefore follows that the ice will be thinner where the ablation is greatest and will increase in thickness as the nett ablation decreases approaching infinite thickness as the snow line is approached. The lakes in this region are rare in the world because few places are so cold and so arid. Although there are many perennially ice covered lakes in the McMurdo Oasis region this type of lake is extremely rare in the world as a whole because summer melting in other regions can ablate a greater thickness of ice than can be produced by winter freezing.
Thus to summarise, the lakes of the McMurdo Oasis Region are of interest from a limnological point of view because in this cold and arid region are found perennially ice covered lakes which are the extreme class of lakes. These lakes present the apparent paradox of containing liquid water in a region whose mean
Returning now to the problems presented by the heat balance of these lakes:
How does liquid water survive in a lake in a region where the mean annual temperature is -20°C? Firstly, it is heated by the inflow water which may be one or two degrees above freezing and which sinks to a depth in the lake appropriate to its density. The maximum density of water is at a temperature of 4°C.
Secondly, most of the heat lost by conduction during the winter is provided by the latent heat of fusion of the water that freezes into the bottom of the ice to replace that lost by ablation.
Some of the lakes have temperatures considerably higher than 4°C and an alternative source of heating must be found. In Lake Vanda, for example, the bottom waters are 26°C. It was in attempting to find the source of this heating that V.U.W. scientists first became interested in Antarctic lakes. The author together with 6. Because of the arid climate in this region the lakes are snow free during the summer. The ice
Let us consider the quantitive aspects of solar radiation and, assuming that the radiation through the water is attenuated exponentially, we have
0e− ax
where Q is the amount of energy/unit area/unit time, being radiated down past a horizontal plane at some distance x below some arbitary zero depth: Q0 is the energy reaching the depth x = 0; and a = 0.693/x1 2. where x1/2 is the distance in which the radiation Q is converted into heat being absorbed either in the lake water below depth x or on reaching the bottom. Assuming no convection (because of strong density stratification). the amount of radiation energy passing downward past a depth x, plus the amount of heat conducted through the lake water, must equal the amount of heat conducted out the bottom of the lake (C).
0e−ax − k dT/dx = C
or
0/k e − ax −Dx+F
which integrates to:
0e- ax/
where T is the temperature, K the thermal conductivity of water, and D and F are constants, a is obtained by bolometry. Taking Lake Fryxell as an example (7) if we fit the appropriate plot of equation (1) to give dT/dx = 0 at the right depth and to give the right temperature gradient and temperature at x = 0, a calculated curve such as that in Fig. 4 is obtained.
Since the initial work on Lake Vanda6 the water of all the lakes in the McMurdo Oasis area which contain water have been shown to be solar heated to some degree7,8,9 — even Lake Joyce which has over 22 feet of ice cover. Lake Vanda is by far the most spectacular naturally solar heated lake in the world. However in recent years the Israelis10 have constructed artificial solar
What of the future? Lake Vanda and the other lakes of this region provide a very large experimental system for studying many problems, for example, heat transfer, diffusion isotope separation. They provide one of the few naturally occurring non-convective systems in the world. Almost certainly the lakes of this region will provide topics of scientific study for some considerable time to come.
Dept. of Zoology, The Australian National University, Canberra A.C.T., Australia
Dept. of Zoology, Victoria University of Wellington, New Zealand
THE PRESENCE OF mummified seal carcases in both glaciated and ice-free regions of McMurdo Sound was first reported by early British expeditions (Scott, 1905; Wilson, 1907). Dead crabeater seals (Lobodon carcinophagus) were found as much as 35 miles inland on the surface of a glacier more than 3000 feet above sea level. Similarly, Weddell seals (Leptonychotes weddellii) were found 20 miles inland at heights of 2400 feet (Wilson, 1907) and one Weddell seal was found at 5000 feet (Scott, 1905).
More recently Péwé, Rivard and Llano (1959), Bull (1959), Balham (1960), Caughley (1960), and Claridge (1961) have reported the presence of carcases inland in the McMurdo Sound region. Several Russian authors including Evteev and Arseniev (1960) have discussed the discovery of seal remains on the Scott Glacier and Bunger Hills on the Knox Coast and also 800 km. west of Mirny in the Larseman and Vestfold Hills.
During the summers of 1957-8, 1958-9 and 1959-60 three small expeditions from the Victoria University of Wellington, New Zealand, investigated about 2500 square miles of ice-free lowland valleys and mountain divides forming part of the deglaciated area lying to the west of McMurdo Sound. A variety of geological and geophysical studies were carried out by these exploratory parties (Bull (1959), Bull, McKelvey and Webb (1962), etc.). The ice-free terrain bounded on the north by the Miller, Cotton and Debenham Glaciers and in the south by the Taylor Glacier which was investigated by the Victoria University of Wellington parties was an area unknown to previous expeditions, although adjacent ice-free areas were visited by field parties from Scott's expeditions of 1901-4 and 1910-13, by Shackleton's expedition of 1907-9, and by numerous parties from more recent expeditions.
Bull, McKelvey and Webb (1962) have described the general area as follows:
The high ice plateau of eastern Antarctica … is bounded at approximately long. 16° E. by a coastal mountain chain extending from lat. 70° S. to 85° S. North of lat. 79° S. this chain lies within Victoria Land.
The greater part of Victoria Land is completely glacierized; major glaciers flow eastwards from the inland ice plateau through the coastal ranges to the Ross Sea. Extensive névé fields in the coastal ranges feed alpine glaciers which flow to join the main valley glaciers.
However, in the area between the Miller, Cotton, and Debenham Glaciers (lat. 77° S.) and the Taylor and Ferrar Glaciers (lat. 77° 45' S.), similar east-west trunk glaciers have retreated, leaving approximately 4000 km.2 of lowland valleys and separating ranges almost entirely free of ice …'
Westwards this ice-free area is bounded by the inland ice plateau, which rises from 6500-8000 feet to 9800 feet at long. 150° E. To the east for about 36 miles north of Cape Bernacchi the piedmont of the Victoria Land mountain range is covered by the Wilson Piedmont Glacier, which forms the coastal boundary of the ice-free area.
The mummified seals described here were found in the ice-free valleys lying between the Asgaard. Olympus, and St. John's Ranges which form units of the Victoria Land mountain chain. These ranges extend eastwards for 35 miles from the inland ice plateau, traversing the deglaciated region in an east-west direction, to meet the coastal plateau. The Wright Valley and the Victoria Valley System form the major valleys of this area and both have a general east-west trend, extending for 25-30 miles towards the inland ice plateau (Fig. 1).
The Wright Valley is blocked at the mouth by an extension of the piedmont ice, the Lower Wright Glacier. Commencing at a height of 1300 feet above sea level the ice-free floor of the valley descends westwards for some 19 miles to about 250 feet above sea level at Lake Vanda. The ice-covered lake is about 4.3 miles long and to the west of Lake Vanda a flat-topped feature, Dais, divides the valley into the North Fork and South Fork, which contain thick moraine deposits. The floors of these valleys rise gradually for a distance of 5 miles, then rise steeply to about 3000 feet and unite in the dissected dolerites of the Labyrinth, which extend westward to the Upper Wright Glacier. Flowing inland from the Lower Wright Glacier is the Onyx River, which meanders across the valley-floor flood plains for 19 miles to Lake Vanda. The ice-covered lake has no outlet and its waters derived from the eastern cirques, alpine glaciers and the Lower Wright Glacier are dissipated by evaporation and wind ablation of the ice cover.
The Lower Victoria Valley is formed by the convergence of the Upper Victoria, Barwick and McKelvey Valleys and extends eastward to the Lower Victoria Glacier, a lobe of the Wilson Piedmont Glacier. The floors of these valleys are thickly covered with moraine deposits and are higher than the floor of the Wright Valley east of Dais. The ice-covered Lake Vida occupies the lowest point of the valley system, extending for about 3 miles at an altitude of approximately 1150 feet. The lake collects melt water from both the Upper and Lower Victoria Glaciers and from adjacent glaciated cirques.
The Victoria Valley system and the Wright Valley are connected by a high level pass, Bull Pass, with an entrance some 2000 feet above the adjacent floor of Wright Valley. The northern entrance of Bull Pass slopes gently to join McKelvey Valley, whose floor lies above that of the Wright Valley.
The Wilson Piedmont blocks the entrances to the major ice-free valleys of the area and in the north merges with the Debenham Glacier. The piedmont glacier is from 3 to 10 miles wide and is almost 1000 feet thick east of the Wright Valley (Bull, 1959). The coastal edge of the Wilson Piedmont Glacier is fringed by a band of moraine deposits (about 2 miles wide) between Gneiss Point and Cape Bernacchi. For the greater part of its length the Wilson Piedmont has steep ice cliffs on the seaward side. However, access to the piedmont can be gained north of Gneiss Point and near Hogback to the south. The Wilson Piedmont Glacier rises steeply to about 1800 feet, then falls gradually to 1300 feet at the entrance to Wright Valley. The piedmont ice approaches to the Wright Valley are less severe than those of the Victoria Valley, for the Lower Victoria Glacier is steep, rough, and narrower than the Lower Wright Glacier, presenting a formidable barrier to access from the coast.
The seal carcasses described here were found by the various field parties of the Victoria University of Wellington Expeditions. A proportion of the carcases found were examined in detail during the summers of 1957-58 and 1958-59 by Barwick, and by Balham in 1957-58 and 1959-60 seasons.
The geographical location, altitude and situation of each seal carcase were recorded together with detailed biological observations. Routine photographs were made and samples for radiocarbon dating were collected from a number of carcases. The position
Seal carcases were found throughout the two valley systems, and were encountered by all field parties engaged in traverses. During the three summers of 1957-58, 1958-59 and 1959-60 the area was travelled by field parties who moved on foot along the valley floors, across the mountain ranges and to mountain summits within the area. The journeys of the various parties comprise about 1000 miles of unduplicated traverses through the region; since the light-coloured seal carcases can be seen for several hundred yards across the moraine-covered valley floors, it is likely that the seals recorded represent a high proportion of the more complete remains to be found in the area.
The majority of carcases were found in the lower parts of the valley floors: this was particularly true of the Wright Valley carcases. Two-thirds of the carcases examined in detail were pointing either up-valley or down-valley, while the remainder showed a random heading in relation to topography. The approximate position of each carcase found is indicated on the map (Fig. 1), which also shows the substrate of each site. Seal remains occurred on both moraine and basement-rock substrates representing all four glaciations distinguished by Bull, McKelvey and Webb (1962).
In general, overall distribution appears to be determined by topography, assuming that the seals migrated inland along the valley floors. The largest concentrations of seals were found in the North Fork of the Wright Valley, the floor of which lies more open to the main valley than that of the South Fork, which is blocked by moraine ridges. In the North Fork 35 seals were found, but only 3 were located in the South Fork. Most of the North Fork seals occurred in two groups (Figures 1 and 2, Group B; Group C). Group B consisted of 12 seal carcases lying within a 150-yard radius of a small saline pool in a large kettle-shaped depression about 150 feet deep. The steep sides would have provided easy entry for seals and the depression formed a natural trap. The second group of 14 seals (Group C) were scattered at the western end of the North Fork at the point where the valley floor joins the steep slopes at the end of the Labyrinth, which forms a natural barrier to the further progress of any seal.
One other concentration of seals was reported in the Wright Valley; a group of 19 seals was found by a geological party at
In the Wright Valley the remains of 88 seals were found, but only 30 seals were located in the Victoria Valley. This difference possibly reflects the relative ease of access to each of the valleys from the coast across the Wilson Piedmont Glacier. The approaches to the Wright Valley are at a lower altitude and are less severe This difference was ascertained by one of us (R.E.B.) during a foot-traverse of the Wilson Piedmont Glacier.
Figure 2 shows the distance from the coast of seals recorded in each valley. The distance is calculated as the shortest route to each carcase site across the Wilson Piedmont Glacier from the sea. In the valleys, seal remains were found almost 40 miles from
The maximum altitude at which seal remains were encountered was approximately 3000 feet, in the North Fork of the Wright Valley and on the western slopes of the Insel Range in the Victoria system 30 miles from the sea coast.
The condition of the remains of the 121 seals varied considerably. The climate, essentially desert-like, produces dessication and ultimate mummification; the mummified carcases become eroded and are eventually destroyed by wind-blown granitic sands which are aided by the effects of freeze and thaw and the prolonged periods of summer sun. Almost all of the seals examined were eroded on their exposed surfaces (Plate 1, Figure 1), but the surfaces which were not exposed generally retained a covering of hair (Plate 1, Figure 2), and many of the carcases had a distinct seal odour.
The remains found ranged from complete, uneroded carcases to weathered fragments of skin and bone only a few inches long. No signs of organic decay were found in the better-preserved carcases. Skua gulls (Catharacta antarctica lonnbergi) are occasionally seen in the valleys but only one carcase showed signs of damage by birds, and this was confined to removal of the exposed eye of the seal.
The remains can be grouped according to the stage of erosion exhibited. These stages, somewhat arbitrarily determined, are as follows:
Figure 3 shows the number of seals placed in each of these groups and in subgroups intermediate to the more clearly defined erosion stages A to F. Group G, termed ‘minimal remains’ contain the miscellaneous fragments of seals found remote from other remains and considered to be those of seals destroyed by erosive processes.
Species could not be determined in many of the seals examined in detail since the carcases were considerably eroded. The species of 41 seals could be accurately determined, while identification of another 8 is uncertain. Of these 35 were identified as crabeater seals (Lobodon carcinophagus (Jaquinot and Pucheran)), and another 5 are probably of this species; 6 were found to be Weddell seals (Leptonychotes weddelli (Lesson)) and another 3 were tentatively identified as Weddells. Earlier reports also indicate that crabeater seals are the species commonly found in the dry valleys. Péwé, Rivard and Llano (1959) reported that all except one of the identifiable carcases were crabeaters, the exception being a leopard seal (Hydrurga leptonyx). Similarly Caughley (1960) notes that all 28 seals encountered in the Taylor Dry Valley were crabeaters.
The length of the better preserved crabeater seals was measured from the tip of the snout to the tip of the tail. Since mummification produces considerable arching of the body, the measurements often had to be made along an axis corresponding to the position of the vertebral column. The measured body lengths ranged from 40 inches to 66.5 inches, and are graphed in Figure 4, which also shows the growth pattern of Ross Sea crabeater seals in relation to the time of year (after Lindsey 1938). The length of 40 inches is 4 1/2 inches less than the minimum length recorded for crabeater seals (Racovitza 1900). It is possible that shrinkage occurs during mummification and that all the length measurements have been proportionately reduced from those of the living animal. The body
The best preserved carcase was found in the north arm of the Wright Dry Valley some 39 miles from the coast. Before death the animal had bled profusely from the mouth and from wounds on the abdomen (Plate 1, Figure 3). This seal lay on a glacial moraine substratum and the blood-soaked sand beneath the mouth and abdomen suggested that it had died where it was found. On dissection the viscera was found to be suffused with blood and some bleeding had occurred into the abdominal cavity.
The fat layer beneath the skin at mid-abdomen was extremely thin (about 3/16 of an inch thick). Unfortunately the carcase could not be removed for detailed laboratory examination. Bertram (1940) notes that in summer the thickness of blubber over the adult body is 2 to 2 1/2 inches. Evidently there is depletion of blubber through starvation as the animal moves inland. In this animal the stomach was full of sand and gravel typical of the moraine beneath the carcase, and several older carcases were also found to have gravel-filled stomachs. The volume of moraine gravels in these these stomachs appeared to be greater than that noted in the stomachs of animals killed inshore during the summer (Bertram 1940, p. 80).
Several of the better-preserved carcases were scarred and cut in the mid-abdominal region (Plate 1, Figure 4), and there were minor longitudinal or transverse cuts about the anus and beneath the chin. Scars are not usually found on young crabeater seals (Lindsey 1938). There were apparently recent injuries, consistent with travel across rough moraine. Some of these wounds had bled, forming a congealed pad of blood, sand and gravel where the carcases lay on the moraine substratum; suggesting that the animals had also lain undisturbed since death.
Carcases were also found on a moraine-free basement rock in the valley floors; only two of these appeared to have been transported by water-action since death, and one other seal was found partly buried in moraine debris. All others were surface deposits, either on moraine or on basement rock foundations, with no indications that they had been transported since death.
Thus there is strong evidence that the seals have entered the valleys and travelled to their present locations over ice-free moraine.
Two radiocarbon ages were obtained from material collected in the dry valleys:
1. A sample from a complete carcase found near Lake Vanda (seal No. 7) gave an ‘age’ of 100 years (Plate 1, Figure 5 and Table 1).
2. Material from a portion of a seal (tibia and hind limb bones, seal No. 36, Group B) classed as ‘minimal remains’ gave an ‘age’ of 780 years (Plate 1, Figure 6).
If these two ages are examined in conjunction with the apparent erosion series (Figure 3), certain conclusions may be drawn. Of the 72 carcases examined in detail, 59 or 81 per cent showed less erosion than the specimen aged 780 years; for purposes of comparison these carcases are thus held to be younger than Sample 2. Within the Wright-Victoria Valley systems 121 seals have been found: if the above deductions are correct, approximately 100 of the seals have ventured into the valleys during the last 780 years; thus one arrives at an average rate of one seal entry into the region approximately every 8 years.
If a similar calculation is made with regard to the carcase aged 100 years, 13 of the 72 carcases studied, or 18 per cent were apparently younger than Sample 1. An extension of this figure gives an average rate of one seal entering the valley every 4 years. Accordingly, this erosion series of carcases, together with the two carbon dates, indicate that the entry of seals into the valley systems has occurred over a long period of time, probably at an average rate of about one every 4 to 8 years.
Claridge (1961) observed some 20 carcases in the Taylor Dry Valley and suggested a rate of one every 100 years.
Péwé, Rivard and Llano (1959) reported on ninety mummified carcases in ice-free areas of McMurdo Sound, and gave a single
With regard to the Lamont contemporary wool standard.
In addition to seal remains, the remains of two Adelie penguins ( Pygoscelis adeliae) were encountered: one in the South Fork of the Wright Valley, 40 miles from the sea-coast, and the second at the foot of the Lower Wright Glacier 10 miles inland. The South Fork penguin gave a radiocarbon ‘age’ of 560 years.
Crabeater seals pup in the early spring, September to October, well out in the pack-ice far from the coast. Bertram (1940) shows that there is good evidence for an inshore migration of the crabeater seals from the pack-ice to the clear waters about the coast in summer when the pups are 4 to 5 months old. The populations spend the summer months inshore and normally return to the pack ice in autumn. Some crabeater seals, however, have been observed to winter inshore in a similar fashion to the Weddell seal (Bertram). Bertram also notes that the stomachs of four crabeater seals shot inshore in early spring were empty and suggests that they had perhaps been forced to starve beneath the fast ice.
Caughley (1960) states that all 28 seals he examined in Taylor Dry Valley were less than mature size. He regarded the presence of dead seals as the result of the ‘quite normal dispersal’ of seals which were unfortunate enough to have their ‘noses pointed in the wrong direction at the beginning of their journey’.
We suggest that the presence of these crabeater carcases in the dry-valley systems might be the result of the following circumstances: some of the immature seals fail to join the general northward migration in autumn; the random dispersal of these non-oriented young combined with the directive effects of major land features, results in the entry of the seals into the dry valley systems. Death through starvation ensues, and since the seal carcases are not buried by snow or ice they mummify. Thus a proportion of the randomly-dispersed immature animals that have failed to emigrate to pack ice in autumn are preserved to view in the ice-free valleys.
The authors agree with Markov (1960) that the seal mummies are found in places to which they have migrated, and that there is no reason to believe that the remains point to a warmer post-glacial climate as postulated by Evteev (1962) who considered that during a ‘climatic’ optimum the pack ice moved south. Thus he explains why crabeater seals were found ‘so far from their contemporary range’. However, there is no need to go to these lengths to explain the presence of crabeater seals in the area for as stated above, there is good evidence for a movement inshore of the seals during the summer (Bertram, 1940). Furthermore, it is evident that seals, both crabeater and Weddell,
An Old Adage has it that ‘Fools rush in where angels fear to tread’; and people hearing that a non-zoologist has had the audacity to write a book on the animals of New Zealand might be led to believe that the author must indeed be a fool if ever there was one. Well, don't be taken in. The author is an arts graduate with—I understand—an M.A. in English; but she has also done some biology in her degree—not that this short incursion into biology is of itself adequate background to launch a project such as the one under review. However, she comes from a family steeped in N.Z. biology, and during her lifetime has obviously saturated herself with knowledge about N.Z. fauna from scientific works, from teaching it at Correspondence School, and from getting out in the field and ‘doing it herself’. I doubt if any practising biologist in N.Z. would have a background quite like hers with which to undertake a similar project. This knowledge of field zoology and her ability to communicate it to the reader have produced a work of value.
This book is written not for the qualified zoologist but for the uninitiated, the interested and the enquiring—both young and old. So one must not look at this book solely through the eyes of a critical zoologist. Although I can claim some familiarity with sections of zoology, I am not a zoologist: but I think that hardly matters. In not being close to the dissecting board I am perhaps better able to view this work in a wide context than perhaps a zoologist could because of his occupational hazard—specialisation. Due to this, many see only the trees and not the wood.
It must always be remembered that the best laboratory in the world is right outside our windows; but it is regrettable that many familiar with it have not done much about writing a manual to acquaint the interested and the enquiring with its contents. To my mind,
Another thing I like about the book is that the zoology does not come out in large indigestible hunks, rolled in choking terminology and all served up cold in a constipated style of writing. Right throughout there is an enchanting use of the best seasoning and aperitifs one can obtain—personal experience and anecdote, which make the subject matter incomparably more appealing than much of the scientific writing one has to stomach. There is also a glossary of terms at the back which will be very useful indeed.
If we understood triggering mechanisms and how they work in animals we would come to know a great deal about animal behaviour. Likewise,
I sincerely hope that necessity demands the appearance of a second edition; and if this is so, there are two suggestions I would make. First, I think a map of N.Z. should be included, not only for the benefit of buyers who are not N.Z.-based but also for the indigenous folk, because it is really surprising how many of us are hazy about our own coastline and other geographical features. For a little extra effort this map could show the main biological zones of N.Z. This inclusion would add little to the cost. The second suggestion may be more costly to implement but I think it would be worth while. Seeing that the book is directed to those unfamiliar with zoological terms, it would be useful to give phonetic pronunciations with stress accents of some of the more difficult words. With this aid it would be easier to mouth such words as ‘Sipunculoidea’, ‘Eulamellibranchiata’, ‘Recurvirostridae’; and who but the initiated would know that the ‘g’ of Chaetognatha was silent, similarly the ‘p’ in Apterygota and ‘C’ in Ctenophora.
One can almost hear the symphony of sighs of the secondary school teaching fraternity when they become aware of the fact that a book of this nature is at last available. They will now have easy access to a reference work that is going to eliminate a lot of conjecture and calculated guessing. No doubt many mothers and fathers will also be very pleased to include this book in their reference library. Now they will be able to refer their enquiring offspring to ‘Animals of New Zealand’ to look for the answer that will eliminate the embarrassment of admitting once more that the fountain of family knowledge is running dry. And who knows but that some parents might also respond to triggering mechanisms and find through being forced to read this book that the Laboratory outside contains untold things of interest, and that they are not too old for adventure and enjoyment in these Elysian fields.