GLACIOLOGY OF THE SOUTH ORKNEYS. 851 



the upper surface of the ice-sheet. In others there is no evidence in the contours of 

 such a sub-glacial ridge — -merely the terminal rock boss. 



Along the west side of Scotia Bay the ice-sheet is very short, and may almost be 

 described as being all snout with a steepness of slope as much as 25°. Part of it ends 

 on a raised beach and has a large terminal moraine, then there is a break of 100 yards, 

 where the part of the ice-sheet I have called the " Half- Moon Glacier" reaches high- 

 water mark and develops an ice-cliff. South of this again is a snout termination, with 

 some moraine, but mainly coming down just to sea-level. The south west corner of the 

 bay, inside Point Martin, terminates in a fine cirque occupied by a small glacier with, 

 comparatively, an enormous moraine, which in summer dams back a small pool — it is 

 too small to call a lake — behind it. No Bergschrund could be seen, even at the 

 height of summer, in this cirque, so that no evidence was afforded of the sapping action 

 at the head wall of a cirque described by American geologists. 



Moraines. 



1. Surface. 



One or two small surface moraines occur where there are nunataks, or hills covered 

 by a thin skin only of ice, e.g. on the eastern ice -sheet near Ferrier Peninsula, but the 

 material soon becomes englacial, for it cannot be traced for any distance below the 

 nunatak. The same applies to the single boulders which are not uncommon at various 

 parts on the ice-sheets close below the dividing hill ridges. 



2. Lateral. 



A small lateral moraine is formed at one place near Point Thomson, on the west 

 side of Brown's Bay, where the glacier abuts against a rocky bluff", but instead of 

 sweeping round it with merely a shallow moat-like depression, from melting by radiation 

 from the rock as is usually the case in such situations, develops a small vertical ice-face 



Text-fig. 11. — Lateral moraine with terracing. 



with a moraine at its foot. This moraine shows terracing, being made up of three 

 parallel rows of debris superimposed on each other. A section would be like the sketch 

 in text-fig. 11 (see also Plate VIII. fig. 1). The material composing this moraine is 

 particularly noteworthy, inasmuch as it contains many water- worn rolled pebbles similar 

 in appearance to those of the raised beaches. None of the material is striated. The 

 height above sea-level is about 60 feet. This is the only instance where this kind 

 of evidence of elevation of the land has been obtained at such a height. 



