Geological Society. $39 
situ, into blocks of the same forms and dimensions as the erratics of 
the Baltic. I remarked this particularly in Ostrogothland, near Lake 
Roxen. Whether this fissuring of the rocks has been due to earth- 
quakes, or the expansive power of ice in northern regions, or to what 
other causes I cannot pretend to decide; but reefs of such jointed. 
rocks before they emerged from the sea might have afforded an in- 
exhaustible supply of detached fragments, over and around which 
the ice would freeze in winter. One block after another might be 
buoyed up and floated off on the rise of the Baltic when the snows 
melted, or of the ocean during'high tides. 
It has been suggested that large blocks may have been pushed. 
far over the bed of the sea and over the land by a succession of 
waves raised by earthquakes or by hurricanes. Without denying 
that such agency may explain some facts in geology, I may remark 
that we cannot be too much on our guard against assuming violent 
catastrophes where the effects may have been brought about tran- 
quilly, and even with extreme slowness. Let us imagine, for ex- 
ample, a sunken reef of granite in Baffin’s Bay, in about 75° north 
lat., divided into fragmentary masses as above described, and these 
masses becoming year after year involved in packed ice. In a few 
months they may be drifted more than 1800 miles to the southward, 
through the Straits of Belleisle, to the 48° north lat., the ice mov- 
ing perhaps at a slow rate—no more thanamile an hour. We 
might even land upon such ice-fields and be unable to determine 
whether they were in motion or not. After a repetition of these 
operations for thousands of years, the uneven bed of the ocean far to 
the south may be strewed over with drift fragments which have 
either stranded on shoals or have dropped down from melting bergs. 
Suppose the floor of the ocean where they alight to be on the rise as 
gradually as the bottom of the Baltic in our own times. The change 
may be so insensible that pilots may suspect, and yet scarcely dare 
to insist upon the fact till its reality is confirmed by the experience 
of centuries. At length a submarine ridge, covered with the tra~ 
velled fragments, emerges, and first constitutes an island, which at 
length becomes connected with the main land,—in time, perhaps, 
the site of a university like Upsala. Here the question is agitated 
whether the land is stationary, or continually rising beneath their 
feet. Perchance they decide that it is motionless, and yet it con- 
tinues to move upwards, “ E pur si muove,” till by a growth as im- 
perceptible as that of the forest tree, what was once a submarine 
reef becomes the summit of an inland mountain. Here the geologist 
admires the position, number, and bulk of the transported fragments ; 
identifies them with the parent mountains, a thousand miles distant 
to the north; and in speculating on the causes of the phenomena, 
imagines mighty deluges and tremendous waves raised by the shock 
of a comet, or the sudden starting up of a chain like the Andes out 
of the sea, by which huge rocks were scattered over hill and dale 
as readily as shingle is cast up by the breakers on a sea beach. 
But it is time to return from these digressions and to consider the 
other memoirs treating of these and similar subjects which have 
