Relict Fauna of Ennerdale Water; a Problem of Distribution

Abstract

THE presence in Ennerdale Water, Cumberland, of the two crustaceans, Mysis relicta, and Limnocalanus macrurus, characteristic of ‘relict’ lakes which formed part of arctic or sub-arctic seas during the closing stages of the last glacial period, has given rise to speculations about the possibility of a former connexion between this lake and the sea^1,2. Since Ennerdale Water, unlike these relict lakes, is 368 ft. above sea-level—far beyond the amplitude of any glacial or post-glacial changes in the relative level of land and sea—the suggestion was that sea water was possibly pushed up the valley by ice. Recent investigations of cores from the bottom deposits of Ennerdale Water have provided proof that during the closing stages of the last glacial episode, no sea water was present in this lake.