1870.] BROWN—PHYSICS OF ARCTIC ICE. 693 
the most northern Danish post, and the most northerly abode of 
civilized man. Circumstances have only allowed of its being noted 
so far’. 
Hr. Neilssen told me that he considered that Disco Island, op- 
posite Claushavn, was rising, because the glaciers were on the 
increase. I think that if there is no more evidence than this for 
that supposed fact, we may lay it aside as erroneous, because the 
glaciers are undoubtedly increasing by the increase of the interior 
mer de glace on the island, and by the regular descent which 
they are making to the sea. 
I have made an attempt to estimate the rate of fall; and though 
we have no certain data, yet I believe that it does not exceed five 
feet in a century, if so much; so that none of us will live to see 
Greenland overspread by the sea. Here I may point out what 
seems to be a fallacy in the reasoning of those authors who write 
about the denuding power of rivers, and calculate that such and 
such a country will be overwhelmed by the sea in so many millions 
of years. Whatever the land loses by denudation the sea gains; 
and therefore the two forces keep pace with each other. We thus 
see in Greenland two appearances: (1) In the interior what Scot- 
land once was; (2) on the coast what Scotland now is. We will 
therefore proceed in conclusion to point out some of the similarities 
in the latter light. 
_ TY. Apprication oF tHE Facts reGARDING Arctic Ick-ACTION AS BX= 
PLANATORY OF GLACIATION AND OTHER LcE-REMAINS IN BrrraArn. 
Scattered over Scotland and the northern portion of England, and 
part of Ireland, are blocks of stone and grooved boulders on the 
top of high hills, or down in valleys. These boulders generally take 
the line of valleys. All over the country, also, is found a coarse 
clay or earth, mixed with boulders, rocks, &c., pell-mell, and above 
it another, finer clay, also with boulders, but stratified, and in many 
localities abounding with fossil shells, these shells being species now 
living in the Arctic Sea. I need hardly remind the reader that this 
is the Boulder-clay, the Northern drift, or by whatever other name 
it is known. In the eastern counties of England it consists of 
grayel with fragments of various rocks ; in the midland counties, of 
dark tenacious clay or “till,” with boulders; and wherever found, 
these clays &c. are almost always local; i.e. they partake in cha- 
racter of the district over which they lie, in colour, texture, and 
admixture of the underlying formations. In addition, the rocks are 
grooved, and the sides and tops of the hills are worn and furrowed 
as if by some body passing over them. Further than this I do not 
require to introduce the subject; for it is abundantly well known to 
all geologists, and its origin is an endless subject of controversy. 
What my opinion of the origin of these clays &c. is, is already 
1 In the ‘Report of the British Association’ for 1869 (Exeter Meeting), I 
have given a summary of the foregoing observations. 
