1841899085

S. Jewtuchowicz

the morphological development of the present day surface was strongly affected by the bedrock. Therefore a ąuestion arises to what degree, if at all, the pradolina was influenced by the end-moraine lying north of it, and, particularly, by the nearest Kutno end-moraine ridge. For this purpose the origin of the moraine ridge and the various glacial accu-mulation forms in its foreland were investigated.

The study of morphological features of the Kutno end-moraine ridge showed that during the Baltic glaciation vertic£l tectonic displacement, which were formed by the movement of salt structure in the bedrock, occured in the moraine zonę. This movement produced the watershade, which divided the drainage basins of the Vistule and the Odra. The vertical tectonic displacement rejuvenated the valley and broken of the course of some rivers, which crossed the moraines.

The Kutno end-moraine ridge includes hills of crevasse-infilling origin. Moraine zonę deposits often accumulated on glacier. Uneven melting of dead ice formed a steep inclination of layers and their wrenches, slumps and slides (Photos 1—19). Water produced during ablation of ice favoure mud flow. Thus structures called load cast were formed.

No outwash plain occurs in the foreland of the Kutno end-moraine ridge. This indicates that during deglaciation the edge of the retreating ice-sheet did not stop in the investigated area. However, a wide ablation zonę of dead ice existed. Melting was ąuicker and sorting was better in crevasses than in areas where glacier ice was compact.

The study of morphology and the inner structure of Kutno end--moraine hills, and of the glacial land-forms in their foreland shows that the Kutno end-moraine ridge is neither a clacitectonic upthrust nor an accumulation feature formed in front of the ice-sheet. It was formed in the zonę of dead ice and its connection with the pradolina is weak.

Field observations failed to reveal links between the Warsaw—Berlin pradolina and the end-moraines of the Frankfurt stage. The area between these land-forms is covered by formations of ground moraine type, while outwash plains that provide a link between end-moraines and pradolina are absent. During the Leszno stage, the drainage was in the reverse direction and crossed by the investigated area. Therefore the hypothesis that the pradolina owed its origin to end-moraines had to be rejected.

An analysis of river valleys revealed many facts about processes that occurred in the pradolina. The pradolina is an erosional base level for rivers flowing from north and south, and thus the changes in its floor affected the morphology of stream valleys leading to it. To study