THE BORROWDALE VOLCANIC SERIES BETWEEN BUTTERMERE AND WASDALE, CUMBERLAND

Abstract

Summary The lowest 3300 feet of the Borrowdale Volcanic Series are exposed adjacent to the eastern edge of the Ennerdale Granophyre between Wastwater and Buttermere. The succession comprises a lower Andesite Group of at least 3000 feet and an upper Dacite Group of more than 300 feet which in one area are contiguous with groups of andesites and rhyolites respectively, the main outcrops of which are west of the granophyre. The area has been subjected to earth movements of pre-Bala and Devonian age. The regional dip of the volcanic rock is between east and south-east. A thrust fault of the same age as the Devonian folds now separates the Skiddaw Slates and the Borrowdale Volcanic Series. Several high-angled faults of later, but probably still Devonian, age cross the area and trend between north-west and NNE. The Ennerdale Granophyre and associated felsite dykes have been intruded into the Borrowdale Volcanic Series. The emplacement of these intrusions, and the Eskdale Granite to the south, has been controlled by the structure of the Borrowdale Series.