Mountains and hills of England the Pennines (often called "the backbone of England") continues into the Yorkshire Dales, a limestone-dominated area of broad valleys and moorland. The Yorkshire Three Peaks are some of the highest summits in the area, which became a national park in 1954. The Yorkshire Dales end at Skipton, and a short distance to the south is a range of moors that rises up between the urban cores of Greater Manchester and West Yorkshire. The range has no continuous name - the western part as far as Blackburn is called the West Pennine Moors, the eastern part north of the A646 (including
Mountain range strata were removed by erosion over the core of the mountain range and spread as sand and clays across the Great Plains to the east. This mass of rock was removed as the range was actively undergoing uplift. The removal of such a mass from the core of the range most likely caused further uplift as the region adjusted isostatically in response to the removed weight. Rivers are traditionally believed to be the principal cause of mountain range erosion, by cutting into bedrock and transporting sediment. Computer simulation has shown that as mountain belts change from tectonically active to inactive,