Palaeomagnetic sampling

The equipment and techniques have evolved from experience gained from the previous sampling expeditions in 1978 and 1980. Oriented core samples, 25 mm in diameter and 50 to 200 mm long are collected. The corers utilise a modified chain saw and weed eater which have been adapted for attaching diamond tipped coring stems. The cutting fluid is a 60/40 ethylene glycol/water mixture to prevent it freezing at the temperatures encountered. The equipment is similar to that developed and used by us in NZ except that connecting tubes and seals were chosen and tested to withstand the low temperatures. The orienting device is a barrel that fits over the in situ core to which is attached a levelling table holding both a magnetic and sun compass. When the core orientation has been recorded, it is removed and marked before being stored for transport in a magnetically shielded container. For statistical purposes, six closely spaced cores per site are required. The site locations have to be levelled with respect to a marker - preferably a trig station or surveyed summit.

Sirius tillite sampling

After mapping the tillite deposits with a staff and Abney level, the matrix is sampled at varying depth intervals, depending on the deposit thickness. Care must be taken to avoid cross contamination. The deposit, which can be very hard and may be permafrost cored were to be broken up with bolster and chisels. A hand operated percussion tool was specially made for breaking up the harder deposits. The residue from filtering 10 1 of water melted from snow through a five micron filter was to be collected to test for airborne diatoms.