Late Weichselian and Holocene development of the small valleys in the SE part of the Niemcza Hills, Sudetic Foreland, southwestern Poland

Abstract

The deposits which fill the small valleys of the Niemcza Hills in the Sudetic Foreland were accumulated by meandering rivers. There are sequences that consist of both the channel and overbank facies, including lateral accretion deposits and soils. The overbank deposits are composed of redeposited loess, which forms the alluvial loam described in this paper as silty loam. Two main stages of accumulation occurred: Lateglacial/early to middle Holocene and late Holocene. During the first stage, accumulation rates were very low in spite of the drastic climatic change at the Weichselian/Holocene boundary. The second stage was characterised by very high accumulation rates and generally increased slope activity, which was probably a result of human impact and extensive agriculture, present in this area since ca 2300-2500 yrs BP. The mollusc fauna changes according to the valley evolution, at first (stage I) represented by poor, redeposited, mainly cold-tolerant loess fauna, and then (stage II) rich assemblages of snails living in shady and humid habitats