Taking a giant leap forward in time, to between 478,000 and 423,000 years ago (the Anglian glacial period), the whole area was buried in ice. Massive erosion, caused by the movement and melting of the ice, shaped much of the landscape; this sculpting continued during another, more recent (the Devensian), ice age (30,000 to 10,000 years ago) (13).
Little evidence of the Anglian glaciation remains but there are extensive deposits from the Devensian, including the gravelly clays of the valley bottoms, which have been formed into trains of rounded hills called drumlins, especially in upper Wensleydale, Ribblesdale and the Craven lowlands. It also transported rocks from far away and when it melted left behind odd rocks called erratics often perched, as at Norber, on different rocks (14).
Map: The superficial geology of the Yorkshire Dales and Craven Lowlands
Photo: Norber Erratics A perched erratic at Norber, a glacier deposited the Silurian sandstone on the Carboniferous Limestone surface which, through weathering and erosion, has been lowered. © BGS (NERC)
| Alluvium | |
| River Terrace Deposits | |
| Peat | |
| Glacial Sand and Gravel | |
| Glacial Till |
Map: YDRP Drumlins – The pattern of drumlins indicates that ice radiated out from the Dales Ice Centre, located in the Wild Boar Fell – Baugh Fell area west of Hawes.