Middle pleistocene gravel beds between Thur valley and Schaffhausen

In the Middle Pleistocene, gravels of different ages were deposited in valleys formed by sub-glacial erosion and in wide rivers valleys. The filling of the eastern Klettgau channel controlled the subsequent morphogenesis to a large extent. The Middle Pleistocene gravel systems occur as Buechberg gravels, Ittigen gravels and Rinnenschotter. After their deposition, they were partly strongly eroded and, in some cases, completely removed. They were later covered by moraines, lacustrine deposits and younger gravels. These processes generally occurred in several phases. While the Buechberg gravels and Ittigen gravels frequently lie above the predominantly fine-grained fillings of older overdeepened channels, the Rinnenschotter generally lie directly above the rock. Following the erosion of the Buechberg gravels, the 'Basadingen Clay' was deposited and later partly covered by younger Rinnenschotter. The Ittingen gravels that once covered the whole of the central Thur valley were deposited in a fluvial environment far distant from the associated glacier margin. Today, only a few relicts can be found. They are younger than the Buechberg gravels and older than the recent Rinnenschotter (=Schaffhausen gravels or Diessenhofen gravels). The demarcation towards the Thur valley is the result of later sub-glacial gully erosion in the central and lower Thur valley, which removed the main mass of the previously widely distributed Ittingen gravels. (author)