EASDALE, a mountain vale on the west border of Westmoreland; descending from High Raise, on the boundary with Cumberland, 3½ miles south-eastward to the head of Grasmere. It is traversed by a streamlet called Eas-gill; it contains a mountain lakelet, called Easdale tarn; it includes also the foaming cataract, called Sour-Milk force; and it commands, in its lower part, a charming view over Grasmere to Loughrigg.

(John Marius Wilson, Imperial Gazetteer of England and Wales (1870-72))