Aerial view of Kentmere Tarn

Aerial view of Kentmere Tarn in Kentmere, the Lake District, Cumbria.
The Tarn was originally a small glacial lake, but in 1840 the valley was drained to provide better agricultural land. It was found that the lake bed held deposits of diatomite (a powdery mineral composed of fossilised aquatic plants). The diatomite was then mined for various industrial uses and two Viking canoes and a spearhead were discovered in the lake bed. After the mine closed, the hole was flooded and the smaller Kentmere Tarn was created.