It was entirely covered with the bottom moraine of the great ice-sheet of the Glacial Epoch, resting upon Silurian sandstones and limestones.
The prairies in this second table-land are gently rolling, and are covered with drift from the continental ice-sheet of the glacial period.
Of these, the Kansan ice-sheet was the most extensive, and the later ones constitute a diminishing series.
The former of these, representing the bottommoraine of the ice-sheet, are covered with Glacial and post-Glacial clays (partly of lacustrine and partly of marine origin) only in the peripheral coast-region - or in separate areas in the interior depressions.
As the part east of the river was once covered by the ice-sheet, its hills have been lowered and its valleys filled through the attrition of glaciers until the surface has a gently undulating appearance.
During the first part of the Glacial period Russia seems to have been covered by an immense ice-sheet, which extended also over central Germany, and of which the E.
This region presents no striking topographic features except the numerous small lakes which occupy the hollows created by the continental ice-sheet.
The ice-sheet wore down from the hills and filled the valleys with debris until the surface has a billowy appearance.
In the ice-free belt, between the northern ice-sheet and the vastly extendedglaciers of the Alps, the two floras must have found a common refuge and congenial conditions of existence; and this view is confirmed by direct palaeontological evidence.
Some of them are relics of the longitudinal moraines of the ice-sheet, and they run north-west to south-east, parallel to the striation of the rocks and to the countless parallel troughs excavated by the ice in the hard rocks in the same direction; while the Lojo As, which runs from HangOudd to Vesi-jarvi, and is continued farther east under the name of Salpausellia, parallel to the shore of the Gulf of Finland, are remainders of the frontal moraines, formed at a period when the ice-sheet remained for some time stationary during its retreat.