花粉分析
Blea Tarn was designated a SSSI in 1989 because of its importance for palaeo-environmental studies relating to the Devensian and Flandrian times. Pollen analysis from Blea Tarn shows evidence for elm branches being collected as fodder from 3300 BC and forest clearances occurring from around 3000 to 2000 BC corresponding with the dates of the Great Langdale axe factory.