A. DVDP McMurdo Sound/Glacial sediment studies

Drilling in the western part of McMurdo Sound (Fig. 1) ended on November 21 after 65 m of penetration, 52 percent of which was recovered as core. The core showed two major units at the site − 13 m of soft muddy sand with scattered pebbles overlying 52+ m of stratified, slightly lithified and better-sorted sand with virtually no pebbles. Post-depositional deformation of the lower unit suggests that it has been disturbed by grounded ice.

Soundings were taken around the drill site, and show it to be on a broad northeast-trending ridge between the submarine extensions of Ferrar and Taylor Valleys. Bottom samples indicate the sea floor is a mantle of muddy sand with occasional pebbles. The flow is covered with a patchy sponge spicule mat and a fauna largely of bryozoans and coelenterates. A report on DVDP 15 will appear in Dry Valley Drilling Project Bulletin No. 7. Work on the bottom samples, and on other samples collected around McMurdo Sound is being continued as an M.Sc. project by K. Sillars.

B. Late Cenozoic Stratigraphy
Part 1

1. Beds of till are ubiquituous throughout the upper Taylor Valley, although exposure is poor except around the snout of the Taylor Glacier. Here meltwater streams from the Rhone and Calkin Glaciers have cut through till sequences on both sides of the valley. These till outcrops have been described, sampled and measured for pebble fabrics.

   Correlation of till deposits throughout the upper valley will be attempted, using grain size analysis, pebble orientation, mineralogy, sedimentary structures etc. From observations of depositional processes occurring around the Taylor Glacier snout at present this correlation could be difficult, for it appears that deposition of till as sheets is quite rare. In fact the glacial drift can change in character from till to mudflow to fluvial sediments over short distances from the ice front, thus limiting the extent of correlation.

   The presence of till sheets in parts of the valley contrasts with the recent deposits, suggesting that modes of deposition from Taylor Glacier ice have changed with time. Processes of entrainment, transport and deposition of debris, were analysed in an attempt to set up the Taylor Glacier as a model for glacial drift deposition.

   This model was extended to include proglacial, glaciofluvial, glacio-lacustrine and aeolian environments by observation of recent sediment deposition in the Wright Valley and at Cape Chocolate.

2. The Wright Lower Glacier shows signs of active ice ablation from the snout where coarse, angular and moderately sorted ablation till is accumulating. Sand blown by wind on to the glacier is being washed off and concentrated around the snout due to meltwater action.page 7
3. An ice-dammed proglacial lake was probably responsible for the deposition of the stratified fluvial sediments within the terraces at Cape Chocolate, while the surrounding moraines are probably from an enlarged Koettlitz Glacier or Ross Ice Shelf.

D. Taylor Glacier Movement study

Three rows of poles (Fig. 2) were placed on the lower 800 m of the Taylor Glacier. The poles were accurately located by DSIR surveyors using theodolite and tellurometer from three trig stations established on the sides of the valley. The height of each pole above the ice was also measured.

The surveying and height measurements will be repeated during the 1976/77 season to determine the movement and rate of ablation.

Fig. 2. Map showing the location of poles placed on the lower part of the Taylor Glacier.