282 SCOTT'S LAST EXPEDITION 
If we assume the Barrier area is 350 X 350 miles, then we 
get a mass of 16:5 cubic miles. 
The difference in these two interesting figures—16-5 cubic 
miles and 11-7 cubic miles—may be due to an ablation of the 
under surface of the sheet by warm water. However, we may. 
assume that there is sufficient snowfall on the Barrier to account 
for the movement, which is a fact of the first importance. 
At the edge of the Barrier there is a curved ascent, and 
‘doming’ is common in bergs. May not this curving be a result 
of the outward expansion? 
The movement of the northern glaciers seems to be much 
greater than that of the Beardmore and southern glaciers. Per- 
haps it is six times as great. But the slow movement in the south 
may still be sufficient to account for the ice sheet’s advance. 
The fact that the great lateral trench keeps open looks as if 
rival motions were at work. 
As far as 170° W., Campbell says that the 1911 survey 
showed the western edge of the Barrier face to be stable, and 
with no change like that since Ross’s time. Of course there may 
be catastrophic years. We know that icebergs are very plentiful 
in some years in the Southern Ocean. This last summer our 
Glacier Tongue broke away after remaining for many years. 
VII. Mainland Glaciers——There is very little evidence of 
large motion. David says the Nansen Glacier presses out the 
sea ice; but quite probably it is the other way, and due to the 
sea ice pressing against the Glacier Tongue. The movement of 
the glaciers is a measure of the pressure behind; they are, how- 
ever, so cold in these regions that their movement is sluggish com- 
pared with those in temperate climes. 
I do not think there is anything like 13 inches annual snow- 
fall on the Ice Plateau. If there is recession along the coast, 
the same must obtain on the great Ice Plateau. The high level 
moraines decrease in height above the present surface of the ice, 
the débris being 2000 feet up near the coast and only 200 feet 
above near the plateau. However, the Beardmore from its great 
crevasses seems to show extra movement. 
VIII. The Inland Ice Sheet——All our data are hypothetical 
—we are erecting an edifice of theoretical bricks! We may give 
it the area of 3% of the circle drawn with a radius of 1200 miles. 
