Yorkshire Three Peaks - Geology

Geology

In common with neighbouring fells, the Three Peaks are carved from an almost flat-lying succession of sedimentary strata of Carboniferous age. The lower slopes of each of the fells are formed from alternating bands of sandstone and limestone assigned by geologists to the Visean age Wensleydale Group. The upper slopes of each of the fells is formed from alternating bands of coarse sandstone (or 'gritstone') and mudstone all of which are assigned to the Namurian age Stainmore Group but which were formerly referred to as the Yoredale Series. These alternations are considered to be a classic British example of cyclothems. Differential weathering and erosion of the various bands has given Ingleborough and Pen-y-ghent a distinctive, stepped appearance.

Considerable areas of the flanks of each of the fells are covered by peat whilst other areas are blanketed by glacial till notably across the southern and eastern slopes of Pen-y-ghent. Fringing Ingleborough on each side however are impressive areas of limestone pavement.

Extensive networks of caves have developed within the limestone strata such as the White Scar Caves, and potholes which attract cavers from all over the country. It is home to England's highest waterfall at Gaping Gill, where the Fell Beck drops 110 m (361 ft) vertically down a pothole, into Britain's second largest cavern. The beck re-emerges further down the mountain adjacent to Ingleborough Cave, where visitors can take a guided tour of a floodlit part of the cave system. Whernside, being more rounded, is visually less imposing than its neighbours, but its summit is the highest point in North Yorkshire.