Depressions created by underground drainage, known as dolines or sinkholes, are a common karst feature in the Westmorland Dales. They are a sign that limestone lies beneath, even if is not visible at the surface. Most are of a type known locally as shakeholes. These conical hollows form when rainwater seeps down through soil and glacial deposits into underlying limestone, dissolving it and widening cracks. The overlying deposits eventually collapse into the cracks, creating the classic Dales shakehole. These can be found across the area, with good examples around Sunbiggin Tarn, on Ash Fell Edge, Crosby Ravensworth Fell and Wharton Fell.
A typical shakehole, formed when glacial deposits and soil collapse into enlarged cracks in the underlying limestone. © E. Pickett
A shakehole formed above Scandal Beck Limestone on south-west slopes of Crosby Ravensworth Fell west of Orton. © E. Pickett
Despite having thick limestone the Westmorland Dales does not have the major cave systems of the Three Peaks area to the south. Pate Hole near Great Asby is a rare example of a cave in the area. Although normally dry, the entrance becomes a vigorous spring or ‘rising’ after heavy rainfall on the limestone uplands to the south. The main rising for the waters in the cave is believed to be St Helen’s Well at the north end of Great Asby.
The entrance to Pate Hole, known as Pate Hole Mouth, in Asby Gill. © D. Evans
The spring of St Helen’s Well in Great Asby, believed to be the main rising for the waters in Pate Hole. © E. Pickett
Other important features of the area’s limestone landscapes include limy deposits known as ‘tufa’ forming at certain springs and the unusual ‘marl lake’ of Sunbiggin Tarn, one of only around three in northern England, which is fed by lime-rich springs from the surrounding limestone.
The northern end of Sunbiggin Tarn, which is fed by lime-rich springs. The limestone scars of Little Asby Scar can be seen in the background. © E. Pickett
A loose block of tufa at Scale Beck, where tufa crusts are being deposited in small terraced pools. © E. Pickett