I.— The Teschenite-Picrite Sill of Saltcoats, Ayrshire

Abstract

1. Introduction. The Carboniferous rocks at Saltcoats, Ayrshire, are intruded in the vicinity of the harbour by a complex of sills and dykes. Of the sills, the two largest are composite intrusions composed of teschenite and picrite, together with allied rock types. They form two promontories, on one of which is built the quay, and on the other the bathing station and pavilion. The sill which underlies the latter buildings has hitherto lacked a detailed examination, and as the exposures showed clearly the composite nature of the intrusion it was thought that an investigation would be merited. To distinguish it from the smaller sill which underlies the quay and terminates seaward in the Inner Nebbock, it is herein referred to as the Saltcoats Main Sill. The original mapping of the area by the Survey was done by the brothers Geikie, the one-inch map being issued in 1870 and the memoir in the following year. At a later date the relationship of the sill to the underlying coal was described by one of these authors (Geikie, A., 1897, fig. 255). The area was revised by the Survey after 1911, and the results published on the one-inch and six-inch maps. A brief description of the sill is given in the Memoir to Sheet 22 (Anderson & MacGregor, 1930, pp. 267-268). These workers regarded it as the faulted continuation of the Castle Craigs sill at Ardrossan, a mile to the west. This intrusion had already been described by Falconer (1907, pp. 605-607). The This 250-word extract was created in the absence of an abstract