The Old Town stands on an alluvial or fluvial fan made of gravel and pebbles, which were washed up between Fulda and Geisbach. Also in the Fulda valley are found gravel and pebbles from the Holocene that are mostly of alluvial origin. There are layers of flood-deposited loess and loam of Pleistocene origin running through them. The gravel and pebbles are to a great extent made up of Middle Bunter, the most widespread stone here. In the west and east, this layer reaches from the Germanic Triassic on the Stellerskuppe (480.5 m above sea level) and the Haukuppe (446.1 m above sea level) up to 400 m above sea level. In the east, on the Wippershainer Höhe (heights), the layer reaches up to 440 m above sea level. The Middle Bunter's lower limit is found at about 110 m above sea level.