Mass Balance Studies on the Ellesmere Ice Shelf
Journal of Glaciology
IN the next paper Dr. H. Lister reported the results of recent work which included two profiles across the Ellesmere Ice Shelf, one of which ran across Ward Hunt Island. In both profiles an attempt was made to run a level traverse across the shelf. It was hoped that, by doing this before and after the ablation season, it would be possible to find the ablation including bottom melting. However difficulties were experienced both in locating sea-level using bore holes, and in allowing for tidal
... lowing for tidal action, and it was not possible to close the level traverses very satisfactorily; the closure was about 15 in. (38 cm. ). The expedition also studied the salinity of sea-water near the shelf and drilled cores to help identify the origin of the ice. Between Ward Hunt Island and Ellesmere Island itself there was white ice overlying very dirty ice, presumably an ablation layer, and this boundary intersected the surface ridge and trough system uncomformably. Thin-section studies on the cores showed that on the ice rise the material started as snow, while in the area of the embayment in the north-east corner of the ice shelf (from which it is thought the " ice island" T-3 broke away) the ice originated as frozen sea-water, a structure that is similar to that of the troughs of the shelf. Dr. Lister then discussed possible theories of the origin of the ridge and trough system, including glacier pressure, barchan-like dunes, a mechanism in which water, blown from the troughs, would orient them parallel to the wind-rose maxima, and tidal warping. As evidence to help decide between these, the amount of snow lying in the troughs was about 30 cm. compared with about 20 cm. on the crests, so there is more snow in the troughs, however this acts as a blanket and keeps the ice in the troughs warm. The troughs seem somewhat different near the ice front, which may suggest that they form there, and Dr. Lister thought that it was likely that their formation was contemporary with the formation of the shelf, possibly being similar to the formation of pressure ice.