De Geer.j 
460 
[May 18, 
lately traced over large areas by Tschernyschew 1 , are probably of 
interglacial age, though they are not covered by till, as are those 
occurring at the border of the last glaciation. But as their fauna 
contains such boreal and southern species as Oyprina islandica and 
Oardium edule , it is not probable that they could be contemporary 
with the arctic fauna of the late glacial subsidence in Scandinavia. 
On the other hand, it is difficult to believe that the considerable 
oscillation of land in northern Russia could have taken place so 
lately as in postglacial time. Hence there is some reason to 
infer that the deposits in question belong to the interglacial 
period, and it is my opinion that, like the undoubtedly intergla- 
cial deposits before-mentioned, they are still accessible above the 
sea-level only outside of the region which was affected by the 
late glacial submergence. 
Before leaving the changes of level in Scandinavia I must add 
a few words about the latest oscillation, though this is not yet 
quite so well known, and can only to a certain extent be compared 
with the conditions in America. 
After the late glacial upheaval in Scandinavia had proceeded so 
far as to isolate the Baltic basin from the sea, thus forming a lake 
with a true fresh- water fauna, characterized by Ancylus Jluviatilis 
Linne, and after this lake, following the general unequal movement 
of the region, had been partly emptied, then, as I have succeeded 
in showing, a new subsidence of land occurred, by which the out- 
lets of the Ancylus lake were changed to sounds, and a marine 
though scanty fauna migrated into the Baltic. The deposits 
formed along the Baltic, as well as along the western coasts of the 
land during this last subsidence, are now partly uplifted, less in 
the peripheral and more in the central part of the region, but 
nowhere more than 200-300 feet above the sea level. They 
contain a true post-glacial fauna, with many southern forms 
which are never found in the late glacial beds. Between these two 
marine deposits, peat bogs, river channels, and other traces of 
erosion are observed in many jdaces in southern Sweden, showing 
conclusively that at least this part of the land was uplifted be- 
tween the two subsidences. Several of these peat bogs and river 
channels continue below the level of the sea, and such signs of 
Th. Tschernyschew, Travaux ex6cut6s au Timane en 1890; Petersburg, 1891, 
pp. 27, 52. 
