186 THE ANTARCLIC MANUAL. 
information as to the ground covered may be obtained from stones 
and boulders imbedded in the ice itself. This may be best seen in 
the neighbourhood of the spot where glaciers melt or on the edges of 
an ice sheet. If stones are borne on the surface of glacier ice, this 
probably indicates the presence of areas of naked rock (known in 
Greenland as nunataks) rising above the surface of the ice, and it is 
desirable that these should be examined. All that can be learned 
from stones imbedded in the ice of a glacier or ice sheet, carried on 
the surface or imbedded in the body of an iceberg, or dredged from 
the bottom of the sea after having been deposited there by the 
melting of ice, can only give imperfect or general knowledge of the 
geology of the country from which the ice has borne the fragments ; 
but even this information is better than none, and all such occur- 
rences of rock fragments in or above ice, or dredged from the sea 
bottom, should be recorded, and specimens preserved. 
Elevation and Subsidence of the Land.—One question will usually 
present itself to almost every geological observer, and that is, whether 
any coast he may be landing upon affords evidence of elevation or 
depression. In the former case, beds of rolled pebbles or of marine 
shells, similar to those now living on the shore, may be found at 
some elevation above high-water mark. Very often the commonest 
molluses in raised beds are the kinds occurring in estuaries, which 
are different from those inhabiting an open coast. Caution is 
necessary, however, that heaps of shells made by man, or isolated 
specimens transported by animals (birds or hermit-crabs), or by the 
wind, be not mistaken for evidence of raised beds. 
To distinguish the shells transported by animals from those 
uplifted by terrestrial movement, the following characters may be 
used: whether the shells seem to have long lain dead under water, as 
indicated by barnacles, serpulz, corallines adhering to their insides ; 
whether the shells, either from not being full grown or from their 
kind, are too small for food; remembering that certain shells, as 
mussels, may be unintentionally transported by man or other animals 
in their young state while adhering to larger shells; and lastly, 
whether all the specimens have the same appearance of antiquity. 
The very best evidence is afforded by barnacles and boring shells 
being found attached to or buried in the rock in the same positions 
in which they had lived; these may be sometimes found by removing 
the earth or birds’-dung coveriug points of rock. 
If the shore is steep, terraces on the hill-sides may mark the 
levels at which the sea remained in past times, but some care 1s 
necessary not to mistake outcrops of hard beds for terraces. On such 
