320 PROCEEDINGS OF THE GEOLOGICAL socieTy. ([Apr. 19, 
under the surface of lakes, in a quite unaltered condition, that the 
action of simple water, and of such little waves as lakes can produce, 
even when prolonged from the glacial period to the present day, is 
absolutely as nothing; and in sheltered bays, the force of the waves 
is not very much greater than in lakes. Moreover, in South America 
I have seen many boulders lyimg on sea-beaches, exposed to the wash 
of rather open channels, and which, so far from having been de- 
stroyed, yet retaimed their angles perfect. 
Nevertheless it might certainly be expected that boulders which 
had thus been buoyed up by coast-ice during long-continued ages 
would be well-rounded. According to Prof. H. D. Rogers, this is 
the case with the majority of the boulders in North America: those 
at Glen Roy were rounded, but they were composed of granite sub- 
ject to dismtegration ; this likewise is the case with those in the Isle 
of Man: Mr. Cumming however informs me that the boulders, with 
some marked exceptions, ‘“‘ diminish m number and size the further 
we proceed”? from the granitic boss. The boulders on Arthur’s 
Seat, judging from the remarks of Messrs. Maclaren and Milne, are 
rounded. Those near Kirby Lonsdale, which now lie, according to 
Prof. Phillips, 500 feet above their parent rock, are not rounded ; 
but they are composed of slate, a rock very little hable to be rounded, 
and they appear to lie in a sort of train up a valley surrounded by - 
mountais, which must formerly have been a well-protected bay. It 
would be interesting to ascertain whether those boulders which now 
stand highest above the parent rock are more worn than those at a 
lower level, which latter I believe to have been dropped during the 
long-continued buoyiag-up process. 
We have seen that, according to Mr. Lyell, the northern parts of 
the United States did actually subside during the glacial period. I 
am not aware that anyone has attempted to show that Great Britam 
was similarly affected during this same period. The following con-. 
siderations, however, appear to me to render it in some degree pro- 
bable: im Staffordshire there are many great and perfectly angular 
boulders of northern rocks, which almost every geologist believes 
were transported on icebergs, now lying at the height of above 800 
feet above the sea; and on Moel Tryfan, at a height of nearly 1400 
feet, there are stratified beds of the glacial epoch (as known by the 
included shells discovered by Mr. Trimmer), which beds, after careful 
examination, I cannot doubt were deposited in the ordinary manner 
under the sea. On the other hand, the character of the miocene 
formations, on the east coast of England, belonging to an epoch just 
antecedent to the glacial, lead to the conclusion that the land then 
did not kold a level widely different from the present one: if so, 
unless we suppose a great inequality in the changes of level between 
the east and west coasts of England, the land must have sunk after 
the miocene age to allow of the deposition of the glacial deposits at 
the heights above specified. This conclusion accords perfectly with 
Professor E. Forbes’s statement*, that all the organic remains seen 
by him, from the glacial formation, indicate a depth of less than 25 
* Memoirs of the Geological Survey, p. 376. 
