Dr. Hitchcock on some Phenomena of Drift. 265 
river. The country, to the northwest of the ridge in Canaan, 
from whence the blocks started, descends as far as Hudson River, 
say 40 or 50 miles; and it is not till we have gone 100 or 200 
miles beyond that river, that we have any mountains of much 
height. And then, if we can imagine a glacier to start from the 
ridge in Canaan, it must ascend 100 or 200 feet, according to my 
estimate, in order to go over the next ridge into Richmond ; and 
then again ascend Lenox Mountain and Beartown Mountain. It 
is quite as difficult, also, to imagine any cause why the glacier 
should change its course after passing the first ridge. If it had 
gone directly down the north and south valley after going over 
the first ridge, it would not be strange ; but it seems to have per- 
sisted in going over the next ridges. 
A case, which approaches more nearly to the one I have de- 
scribed in Berkshire, is given by Mr. Darwin as occurring in the 
Falkland Islands, south latitude 52°. “The bottoms of the val- 
leys,” says he, ‘‘are covered in an extraordinary manner by myr- 
iads of great angular fragments of the quartz rock. The whole 
may be called a ‘stream of stones.’ The blocks vary in size from 
that of a man’s chest to ten or twenty times as large; and occa- 
sionally they altogether exceed such measures. ‘Their edges 
show no sign of being water-worn, but only alittle blunted. The 
width of these beds varies from a few hundred feet to a mile.’* 
The slope of these streams of stones is about 10°, and they ap- 
pear to have travelled from the heads of the vallies since the land 
was raised above the sea. But Mr. Darwin supposes them to have 
been hurled from the nearest slopes, and then, by powerful earth- 
quakes, to have been leveled into continuous sheets. Did the 
blocks in Berkshire occupy the bottoms of the vallies, this expla- 
nation might perhaps apply to them. But the position of the 
trains in an oblique direction across the hills and the vallies, ren- 
ders this theory inapplicable. In short, I find so many difficul- 
ties on any supposition which I can make, that I prefer to leave 
the case unexplained till more analogous facts shall have been 
observed. 
* Narrative of the Voyage of the Beagle, Vol. III, p. 253. 
