The geology of the Isle of May

Abstract

The Isle of May occupies a commanding position at the entrance to the Firth of Forth, lying five miles from the coast of Fife and ten from that of East Lothian. It forms, however, a distinct danger to navigation in these waters and was for this reason one of the first islands of Scotland to possess a permanent lighthouse, the original one taking the form of a large coal brazier. The history of the island is interesting and chequered, but it has been considered fully in numerous volumes dealing with the county of Fife. Another feature which has received marked attention is its abundant bird life. The geology has, in comparison, suffered neglect, and it was not until the publication of the Geological Survey Memoir on East Fife that the interesting nature of the island became known.1 It was then shown that the Isle of May consists of a single sill of analcite-olivine-dolerite containing a curious dark mesostasis, while an account is also given of faulting, glaciation, and raised beaches. Since then the island has received only passing mention in few publications, which is somewhat surprising in view of its accessibility—for it may be reached from Anstruther (six miles distant) by motor fishing boat on any calm day. The account below is based on a series of visits made to the island during the early summers of 1932 and 1933. Physical Features of the Island. The Isle of May shows marked elongation in a direction N.W. to S.E., and measures