 Volcanic clasts in the Molasse Zone of Upper Bavaria and Salzburg evidence the presence of the volcanoes, which subsequently eroded.The eastern part of the Northern Calcareous Alps was part of an alluvial river plain, which explains the crystalline pebbles now located on high plateaus.The area by the edge of the Alps was pushed down by the weight of the orogenic wedge, forming a foreland basin, which flooded around 34 million years—becoming the inland Molasse Sea from France to Central Asia.