METHODS:

The instrument used was a Worden Master Geodetic Gravity Meter operated without thermostating, because power supplies were not readily available. The temperature calibration of the instrument is known but the results here reported have not been corrected for the small variations in instrument temperature. The corrections involved are negligible compared with errors arising from other sources.

Values of gravity were measured at 17 points along the valley, at approximately 2 km intervals. (Fig. 1) The value of gravity at the Base Station near the end of the Taylor Glacier was determined by two linkages (by U.S. Navy helicopter) with the established gravity stations at the U.S. McMurdo Station 13, and Scott Base Gravity Station 2. The traverse along the valley was made on foot, the interval between the two readings at the base station being 25 hours.

Gravity stations were located at geographic features which are easily recognizable on the existing aerial photographs and on the 1:50,000 planimetric and 1:100,000 topographic maps of the area produced by the United States Geological Survey, Special Maps Division, Washington.

The altitudes for the gravity stations given in this report were obtained with a small temperature-compensated hand altimeter. As given here they are probably not reliable to better than 50 feet, and at stations 10 to 16 inclusive the error may be larger. However the altitudes of the stations were measured again later in the season with better altimeters. Further, most of the stations are on the edges of lakes, the altitudes of which have been calculated by aerial triangulation methods during the process of map construction, by the U.S. Geological Survey. Final values for these altitudes should be correct to about 20 feet.

In reducing the data it has been assumed that all of the rock between the gravity stations and sea-level is of density 2.67 gm.cm.⁻³. No allowance has been made for the lesser density of the glacial deposits at the mouth of the valley, but the errors arising from this should not exceed 5 milligals. Terrain corrections have not-yet beep applied. These may amount to 10 milligals (1 milligal = 0.001 cm. sec⁻².) at stations 11 to 16 inclusive, but elsewhere they should be smaller and the application of the correction will not appreciably alter the overall picture presented by the results.