Zur Problematik der pleistozänen und holozänen Vergletschernung Süd-Kamtschatkas – erste Ergebnisse bodengeographischer Untersuchungen

Abstract. In the Plotnikova Valley, west of Petropavlovsk in South Kamchatka, two valley drift complexes can be identified. They are correlated with glaciofluvial terraces. The older, so called M1-moraines descend to about 300 m a.s.l. corresponding with the T1-terraces; they are smoothand vague-shaped, without kettles. The younger, so called M2-moraines descend to 350-450 m a.s.l.; their relief is well formed and rich in kettles and ridges, and they are connected with the T2-terraces. The soils developed on these drifts and terraces do not differ significantly with respect to colour and weathering intensity. Soils of the older drift and terraces reveal stronger cryogenetic disturbances and their boulders and gravels are characterized by more pronounced weathering crusts in comparison to the younger drift and terraces. No features indicating interglacial weathering can be identified in the subsoils. But all soils are stratified by 3-4 tephra layers, due to the following eruptions: tephra 1 = Opala, 1400-1500 a BP; tephra 2 = Ksudach 1, 1700-1800 a BP; tephra 3 = Ksudach 2 = 6000 a BP; tephra 4 = Kuril Lake Il'inskay, 7600-7700 a BP (BRAITSEVA et al. 1992). According to these results it is supposed that both moraines indicate Late Pleistocene glaciation; the M1 drift was deposited during an early phase of the Late Pleistocene, the M2 drift characterizes a second phase of the Late Pleistocene, separated only by an interstadial, not by an interglacial. In contrast to Middle Europe, early Late Pleistocene glaciation has been more pronounced than Late Pleistocene second phase glaciation. Studying soil development on frontal moraines along a sequence from 350 to 1000 m a.s.l. in the Topolovaya-Valley it was found that up to about 930 m a.s.l. all soils are stratified by tephra 1-4 layers, indicating that the age of the corresponding moraines is older than 7600/7700 a BP. Drift in about 980 m a.s.l. shows only tephra 1 and 2. These moraines are older than 1700/1800 a BP, but younger than 6000 a BP. Probably they indicate a glacial advance during the middle Holocene (Neoglacial). In 1000 m a.s.l. two additional ridges can be identified, well formed with initial soil formation but without tephra. According to the lichenometric results they characterize snow and ice accumulations during the so-called "Little Ice Age".