DENUDATION BY ICE-ACTION. 
93 
Ice-action. — Adopting the same plan as before, we shall briefly review the general 
action, as a geological agent, of each specified form of ice. The sea-ice, as already 
pointed out, seldom runs aground, and is therefore negligible as an agent for striating 
or abrading rocks or for contorting beach-deposits. Sea-ice forced up on to the land 
has been observed at only one spot. This was the very exposed north-east corner 
of the stranded moraines on the west side of McMurdo Sound, where sorting' and 
rearrangement of the moraines is so constantly happening that no permanent effects 
of sea-ice could be traced. As a transporting agent, sea-ice is not very effective. 
Sometimes a boulder may roll across the fringe of shore-ice on to it and be taken 
out to sea. The original boulder may be angular or it may be ice-scratched ; its 
condition when on the ocean-floor can hardly be said to indicate its method of 
transport. Dust and fine sand are often blown on to sea-ice and may then be 
further transported. In 
Wood Bay great numbers 
of pumice-pebbles (899) had 
been blown on to sea-ice, 
which would be drifted far 
to the North by the preva- 
lent ocean-currents before 
it melted. 
The shore-ice has a 
conservative * effect upon 
the land. It binds together 
the talus of the hills, and 
so protects talus and rock 
from the eroding action of 
drifting ice-floes or waves. 
When a piece of an ice-foot 
floats out to sea it usually 
carries a great load of debris. Stones roll on to the surface, and, through the 
melting of the ice around, work downwards. Pockets of dust ( Kryokonit )f are 
exceedingly numerous ; probably also much rock-material is held within the sole. 
All these must be transported. As ice which has left the shores of South 
Victoria Land seldom grounds, the abrading or striating action of shore-ice there 
must be small. 
The glaciers taken as a whole are not now modifying the form of the land to 
any great extent. The corrie-glaciers and ice-slabs appear to be aggrading rather 
than excavating the valleys in which they lie (Fig. 56). The corrie-glaciers at the 
Inland Forts have a Beryschrund, but, judging from the small amount of terminal 
* Bonney, Quart. Journ. Geol. Soc., 1902, vol. Iviii, p. 699 ; Bonney, Geog. Journ., 1893, vol. i, pp. 481-499. 
t Drygalski, ‘ Gronland-Expedition,’ 1897, Bd. i, p. 94, ft. 
Fig. 56. — A Glacier descending from the top of Coclman Island 
into the Sea. 
