Lithology of the late valdaian glacial moraine in the western part of the Kola peninsula

A profound study of the moraine has been provided. The results have been grouped according to the basement rocks composition. The basal moraines bedding on disintegration products of crystalline rocks, sandy siltstone sediments in the area of abundant metamorphosed and igneous rocks, and on clays in the sandstones occurrence of the Terskaya Suite have been considered. It has been defined that in the basement of the moraine bed there is a clear dependence of the large detrial material composition and the granular composition of the moraine silt on the basement rocks composition. The dependence considerably weakens upwards the section. The received data testify to the plastic glacier flow having dominated in the region, when layers in the glacier basement shifted slowest and the speed of the glacier movement increased upwards the section. The plastic flow has been associated with shifting along internal splits, which provides the inflow of the detrial material to the upper layers of the glacier. Some faults of the moraine that formed under the Middle Dryas advance of the glacier are considered as erratic mass of sedimentary rocks. Their contemporary appearance formed during the change of the glacier gliding along the bed for its inner shifting along internal splits and by plastic flow. An irregular-structured moraine occurred, when the detrial material in flakes, which lost their plasticity and as a result peeled off the basement of the moving glacier, did not consolidate before each flake peeled off. When the interval between the exfoliation of flakes was longer, the transferred detrial material interacted with the formed moraine. In result of the debris abrasion fine layers enriched by clayey particles occurred. The layers can be observed in a moraine with a bedded structure. The tabular structure was produced under the freezing of the previously deposited moraine. The ablation moraine differs from the basal one in its lower silt content. Along with the Quaternary sediments, the source of the detrial material was the area weathering crust of the hydro-mica type.