A week in late October 1978 marked the end of sedimentological and glaciological field work for the Taylor Glacier project. Paul Robinson and Stewart Ross (DSIR) made an early season trip to Taylor Glacier (Plate I) to complete the englacial sediment sampling and to observe englacial structures before the 'melt' began. This was followed by two weeks (Oct 28-Nov 11) investigation of dry valley alpine glaciers (Rhöne, Sykes, Albreich and Sandy) and two outlet (?) glaciers (Wright Upper and Victoria Upper). Comparisons of the englacial sediment texture, ice structures and the products of deposition indicate that the mechanisms of debris incorporation for these glaciers differ from those of Taylor Glacier. Rhöne, Sykes, Albreich, Sandy, Wright upper and Victoria upper (Plate II) Glaciers contain various types of glacial debris, but none show the strong basal character of Taylor Glacier.

Taylor Glacier sediment ranges in sizes from clay through to large boulders, and is presently depositing this boulder-clay (or till). The percentage of sediment on the ice ranges from less than 1 to 60 per cent, and this, together with the various sediment grain size textures, gives a good indication of the modes of debris incorporation. The predominant process for Taylor Glacier sediment entrainment appears to be basal regelation. This probably occurs 1) by abrasion, pressure melting and the associated "freezing in" of debris at the glacier sole; and 2) by block incorporation of pre-existing till, again by freezing of meltwaters at the base of the ice mass. Although both of the above processes produce similar sediment texture, the sediment to ice concentrations vary (abrasion and regelation less than 1 to 20 percent; till block regelation commonly greater than 15 to over 60 per cent).

The alpine glaciers (including Wright Upper and Victoria Upper, which were previously considered true outlet glaciers) contain diffuse (generally less than 5 per cent sediment to ice), moderate to poorly sorted, angular to subangular sand and pebble debris (Plate III). Such sediment is characteristic of a supraglacial origin, where valley wall rock fall is buried by snow accumulation and subsequently transported englacially.

This project reveals the apparent uniqueness of the Taylor Glacier in comparison to other glaciers terminating on land in the Dry Valleys. However, future observations of glaciers such as the Ferrar, MacKay and Mulock, all plateau-fed glaciers, may reveal an ability to produce basally-derived debris.

Zones of net basal melting and refreezing for the inland ice (Drewry, in press) and Taylor Glacier (Robinson, in prep.) have been determined from geophysical and glaciological data. This is consistent with the already outlined basal debris regelation model. However, for the sediment presently being deposited at the snout of Taylor Glacier incorporation would have to have occurred between 2000 and 6000 years before present. This is based on estimates of present day positions of basal sediment incorporation sites, and assumes present day ice velocities.

Glacial sediments surrounding Taylor Glacier and Lake Bonney exhibit similar features to the englacial material of Taylor Glacier. Therefore, it seems likely that the main process of debris incorporation by Taylor Glacier has been basal, and that Taylor Glacier is, and has been, a wet-based glacier for several thousand years.

The saline discharge at the snout of Taylor Glacier (Black, 1969; Keys, in prep.) was underway during the October visit (Plate I). Temperature measurements of air (−26 to −16°C), ice (−17 to −10°C) and the liquid discharge (−6 to −5 5°C) were made. An estimate of the total discharge was considered to exceed 3000m³.

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While working around Wright Upper Glacier an in situ outcrop of granitic basement was located (Plate IV). Exposure is restricted to 0.5 km² in the N.W. corner of the Labyrinth, but appears to extend under the N.E. margin of the Wright Upper Glacier. Here the Labyrinth dolerite sill has thinned out, so that the overlying Beacon sediments are in direct contact with the granitic basement. These observations are in direct contrast with Claridge and Campbell, 1978. They suggest that no granitic material is exposed west of Koenig Valley, Asgard Range. This previously undescribed outcrop may have significant bearing on the inferred direction of ice movement (Robinson, in press).

In conjunction with Event 1 (Dry valley hydrology), Robinson spent two days at Wright Lower Glacier. Attempts at locating glacier ice beneath lake ice were abandoned when drilling equipment was damaged by coarse sediments 2 m down at the probable lake ice glacier ice contact. Further attempts were to be made later on in the season by Event 1.

References

Black, R.F., 1969. Saline discharge from Taylor Glacier, Victoria Land, Antarctica. Antarctic Journal of the U.S. vol 12 (4): 102-104.

Claridge, G.G.C. and Campbell, I.B., 1978. Moraines of probable Miocene age, dry valleys, Antarctica. N.Z. Antarctic Reocord 1 (2): 1-5.

Drewry, D., in press. Geophysical investigations of ice sheet and bedrock inland of McMurdo Sound, Antarctica. Antarctic Geoscience (C. Craddock, ed.). University of Wisconsin Press, Madison.

Keys, J.R., in press. Some saline and glaciological studies in the McMurdo Sound region. PhD Dissertation.

Robinson, P.H., in press. Eastward ice advances in Wright Valley, Antarctica. N.Z. Antarctic Record. 2 (1).

In preparation - An investigation of entrainment, transport and deposition of glacial debris by polar ice, with special reference to Taylor Glacier, Antarctica. PhD Dissertation.

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