1848.| DARWIN ON THE TRANSPORTAL OF ERRATIC BOULDERS. 3519 
out ; and it is by coast-ice, as I believe, that boulders have been trans- 
ported from a lower to a higher level. 
To take the case of North America: Mr. Lyell* has shown, from 
an independent train of reasoning, that this country during the gla- 
cial period slowly subsided to a considerable amount : several Ame- 
rican geologists have come to a similar conclusion, and they believe 
that the subsidence amounted to two or three thousand feet, or even 
more. Let us suppose a sinking movement to be now going on in 
the estuary of the St. Lawrence or on the coast of Labrador, where 
we know, from the observations of Lieut. Brown and Capt. Bayfield, 
as given by Mr. Lyeli+ (and illustrated by striking sketches), that 
annually an enormous number of boulders, both on and near the 
coast, are frozen into the coast-ice and transported to shorter or 
greater distances ; can we doubt, that if durmg the year the land 
sunk a few inches or feet, the boulders, whilst actually frozen in or 
when refrozen durmg the ensuing winter, would be lifted up and 
landed so many inches or feet higher up on the coast? Capt. Bay- 
field, as stated by Mr. Lyeilt, saw masses of rock, ‘carried by ice 
through the straits of Belle Isle, between Newfoundland and the 
continent, which he conceives may have travelled in the course of 
years from Baffin’s Bay.” Now if during this probably long course 
of years,—for the boulders seem generally to be transported only a 
short distance each winter,—the land had subsided one or two hundred 
feet, is it not almost certain that they would have been landed so 
many feet higher up with respect to their former level, in the same 
manner as would have happened with so much drift timber? It is 
indeed paradoxical thus to speak of the boulders having been carried 
up, whilst the land has gone down; for, in fact, the boulders are 
merely kept by the floating ice at the same level, whilst the land 
sinks. 
No doubt during this process some boulders would be dropped in 
water too deep to allow of their being refrozen, and they would be 
thus left behind. Scarcely any form of land would prevent the 
boulders from being annually landed on a temporary resting-place : 
even a line of perpendicular cliff, if not of very great length, would 
probably only cause the tidal currents to drift the coast-ice further 
onwards ; a few more boulders, perhaps, being dropped there than 
elsewhere. I can see only one difficulty of any weight to this view, 
namely, that the boulders would be ground down into mud and de- 
stroyed from having been stranded such innumerable times, as must 
have happened with those which were kept up to the same absolute 
level during a sinking of the land of many hundred feet. On an ex- 
posed coast, where the breakers had power to dash pebbles against 
the boulders, I have no doubt that this would take place, more espe- 
cially with boulders small enough to be themselves rolled over. But 
on a broken coast, amongst islands and in bays, I do not believe that 
this would happen. We may infer from the fact of scored rocks 
having been observed both in Scotland and in North Wales, dipping 
* Travels in North America, vol. i. p. 99, and vol. ii. p. 48. 
+ Principles of Geology, 7th edit. p. 222. ¢ Ibid. p. 231, 
