Malham Tarn | Malham
Malham Tarn is a glacial lake near the village of Malham in the Yorkshire Dales. At 377 metres above sea level it is the highest lake in England and the highest marl lake in Great Britain. The lake is one of only eight upland alkaline lakes in Europe. The size area of the lake is 600 hectares and at it’s deepest, with an average depth of 2.4 metres.
The lake's basin was dammed by a moraine at the end of the last glacial period, approximately 10,000 years ago. It used to be about twice its current size, having shrunk due to silting at the western shore; this has formed a boggy region called Tarn Moss. Following deforestation during the Iron Age, the land surrounding the lake has been used for grazing which has prevented further tree growth.