The adinoles of Dinas Head, Cornwall (With Plate XI.)

Abstract

Dinas Head is a small promontory adjoining Trevose Head, some five miles west of Padstow on the north coast of Cornwall. Petrographical attention was first drawn to it by Howard Fox, who in 1894, noted the development of albite-rich rocks between greenstone and slate, and he concluded that the rock was an adinole. He also noted the peculiar spherulitic development of albite giving some rocks an igneous appearance, but, on account of the fine banding preserved in these rocks, he concluded that they were metasomatized sediments. This conclusion was subsequently supported by McMahon and Hutchings. The Memoir of the Geological Survey of the Padstow and Camelford district agrees with Fox as to the origin of the adinole, and points out the exceptional thickness of its development when compared with other greenstone-slate contacts.