Abstract:
The main fluvial development stages of the Russian Plain have been revealed. The result is based on the investigations of landforms and deposits of low terraces, flood-plains and river channels of Seim and Svapa rivers. These stages are: 1) 17-19 Ma B.P. - formation of constrative alluvium layers of sand and siltstone more than 10 m thick; 2) 14-17 Ma - formation of the large meandering river channels with discharge 6-7 times more and normal alluvium thick 1.5-2 times more than recent; 3) 10-14 Ma - the reduction of large channels and formation of inherited flood-plains and its deposits; 4) less than 10 Ma - formation of recent meandering river channels and the belt of segment-ridges flood-plain under the conditions of long-period changes of water discharge.
