459 
[De Geer. 
1S92.J 
upheaval may be thus explained : as in continental areas in general, 
this old tract of erosion has probably in the main been one of 
upheaval, while the contrary was the case with the surrounding 
regions, where the sediment was accumulating to a very consider- 
able extent. During the Ice age, among other high lands, the 
Baltic shield received an ice-sheet equal in weight to more than a 
thousand feet in thickness of the rocks which had been eroded 
away during previous periods. As Jamieson long since suggested, 
it is very probable that the crust of the earth must yield and 
subsidence of land take place beneath this added load. There- 
fore it is reasonable that the movements in the crust should be 
chiefly dependent upon its geological structure. 
When the ice-load disappeared, the land partly re-emerged, 
until a balance was reached, which seems to have happened before 
the original height was attained, a part of the change having 
become permanent. 
If the ice-load was the essential cause of the submergence, a 
still larger subsidence must be supposed to have followed after the 
earlier and greater glaciation. It is true that very few traces of 
unquestionable interglacial marine deposits have been found, and 
that these are all along the boundary of the late glacial region of 
upheaval, or in southern Denmark and along the Baltic coast of 
Germany ; but this is just what would be expected. 
Then, as Dana first pointed out with reference to the fiords as 
submerged river-vallevs, the land had probably in the beginning 
of glacial time a much greater elevation than at present. Thus 
it is quite possible, that during the great glaciation a considerable 
subsidence from the highest elevation occurred, followed during 
interglacial time by a partial re-elevation of the land ; while the 
early marine deposits during the late glacial subsidence might 
have been a second time so deeply depressed below the sea-level 
that they have not since been uplifted sufficiently to appear above 
it. According to this explanation, it is easy to conceive why the 
interglacial marine deposits are accessible just in the tracts which 
were least affected by the late glacial subsidence. 
I take this opportunity to remark that in my opinion the marine 
sediments which Murchison, Verneuil, and Keyserling 1 found at 
Dvvina and Petschora in northern Russia, and which have been 
1 Murchison, Verneuil, und Keyserling, Geologie des europaischen Russlauds; 
bearbeitet von G. Leonhard. Stuttgart, 1848, pp. 348-351. 
