Abstract: | Glacial sediments in the eastern part of the
Głubczyce Plateau, at the Krowiarki site, were studied. Two
units were distinguished within the sedimentary succession.
The lower unit is composed of mainly sandy sediments with
diamicton interbeds, the upper unit of very fine silt and clay
sediments that exhibit rhythmic lamination in parts. Based
on the textural and structural features of deposits, local
deformations and palaeoflow directions, it was found that the
sediments had been deposited within an ice crevasse, which
was initially open and functioned as an ablation flow artery.
The sediments were deposited in the form of a small fan
dominated by sheetflows. Glacial tills were also redeposited
on its surface. In a later phase, the crevasse was blocked. As a
result, it was filled with water, leading to the development of
a crevasse lake in which low-energy deposition dominated.
The crevasse style of deposition indicates that, in the final
stage of glaciation, the marginal part of the ice sheet was in a
stagnant phase. This conclusion applies to the part located
on the southern side of the watershed of the eastern
Głubczyce Plateau. The probable reason for the stagnation
of the ice sheet was the distinct loss of ice supply above the
local topography barrier due to the decreasing thickness of
the ice sheet in the studied area. |