This ‘staircase’ of flat topped terraces was created as a result of successive periods of deposition and subsequent down cutting by the river, a product of the meltwater and glacially eroded material produced from ice sheets at the end of glacial periods through the Pleistocene epoch between 450,000 and 12,000 years BP. Contained within these terraces is evidence of the mega fauna that once lived along the river, the bones and teeth of animals such as the woolly mammoth, bison and wolves that existed during colder periods have all been identified. Another notable find in a related terrace system near Derby from a warmer interglacial period, was the Allenton hippopotamus.