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XLIX. The Ice of Greenland and the Antarctic Continent not 
due to Elevation of the Land. By James Croll, LL.D., 
F.B.S.* 
f^BEENLAND. — The only two continents on the globe 
covered by permanent ice and snow are Greenland and 
the Antarctic. But are these continents to be regarded 
as Highlands or as Lowlands ? It is an opinion held by 
many that these regions are greatly elevated, and that it is 
mainly owing to this elevation that they are so completely 
buried under ice. I have been wholly unable to find evidence 
for any such conclusion. It is of course true that, in regard 
to Greenland at least, the observations of Rink, Heyes, Nor- 
denskjold, Jensen, Brown, and others show that the upper 
surface of the inland ice is greatly elevated above the sea-level. 
Dr. Eink, for example, states that the elevation of this icy 
plain, at its junction with the outskirts of the country where 
it begins to lower itself through the valleys, in the ramifica- 
tions of the Bay of Omenak is about 2000 feet, from which it 
gradually rises towards the interior. Nordenskjold, 30 miles 
from the coast, reached an elevation of 2200 feet, and found 
the ice continued to rise inwards. Heyes, who penetrated 50 
miles into the interior, found the elevation about 5000 feet, 
and still continuing to slope upwards toivards the interior of the 
continent. This upward slope is a necessary condition of con- 
tinental ice, and must continue till the centre of dispersion is 
reached. As the larger portion of the Greenland ice is dis- 
charged at the west coast, it is probable that this centre of 
dispersion, or rather ice-shade, will lie nearer to the east coast 
than to the west. There is little doubt that the greater part 
of the surface of the inland ice is far above the snow-line ; but 
this does not prove that Greenland is an elevated country, 
for this elevation of the upper surface of the ice may be due 
entirely to the thickness of the sheet. If the sheet is at least 
1000 or 2000 feet thick at its edge, it is not surprising that it 
should be 5000 feet thick 50 miles in the interior, seeing that 
it is a physical and mechanical necessity that continental ice 
should gradually thicken towards the centre of dispersion. 
It has been shown from physical considerations (' Climate 
and Time,' pp. 374-386) that the thickness of the ice in 
the centre of Greenland is probably upwards of 2 miles, 
and that the Antarctic ice-cap at the South Pole, which is 
most likely not far from the centre of dispersion, must be over 
6 miles In thickness. 
* Communicated by the Author. 
