4+8 
SCOTT'S LAST EXPEDITION 
into the open sea. Examples of this type are furnished 
by ' Glacier Tongue ' between Winter Quarters and Hut 
Point, and by the Nordenskiold and Drygalski ice 
tongues farther north. This latter pushes its way into 
the sea a distance of about thirty miles and has a volume, 
on a rough calculation, of fifty thousand million cubic 
yards. 
Probably the most interesting of the data collected 
on glaciers were connected with their interior structure, 
the size of the individual crystals, the amount of the 
imprisoned air in the form of air bubbles, the occurrence 
of silt bands and of bands of clear blue ice in horizontal 
layers, and the occurrence and distribution of crevasses 
and of pressure ridges in the glacier. This field, however, 
is much too large to enter upon in this place. 
The Barrier 
By far the most unique feature of the Antarctic is 
the occurrence of huge masses of floating ice, such as the 
Great Ross Barrier, which fills up the whole of the narrow 
end of the Ross Sea. This great sheet of floating ice has 
an average depth of probably 600 feet and presents an 
unbroken front to the sea 400 geographical miles in length 
with a depth from back to front of over 300 miles. The 
surface of the Barrier is comparatively level, and offers 
little obstruction to sledging. The yearly snowfall from 
observations by Captain Scott in the Discovery Expe- 
dition and from Sir Ernest Shackleton's work amounts 
to about eighteen inches of consolidated snow of density 
