III.—The Bekinkinite of Barshaw (Renfrewshire), and the Associated Rocks

Abstract

The recognition of teschenites in the Midland Valley of Scotland, first by Teall and later by several other petrographers, has led to the discovery of numerous varieties of analcite-rich rocks in th same area. One of the most interesting of these is the unique rock discovered in an old quarry at Barshaw near Paisley, during the remapping of the district by the officers of the Geological Survey of Scotland. A preliminary description of this rock as a weathered theralite was given by Mr. E. B. Bailey in 1909. In the previous year a chemical analysis by Mr. E. G. Radley had appeared. A fuller description is given in the Survey Memoir on the Glasgow District (1911). According to Mr. R. G. Carruthers the theralite is probably part of an igneous mass which is persistently found at the Hurlet Limestone horizon of the Carboniferous Limestone Series in the Paisley district. Tlie petrography of the rock, as investigated by Mr. Bailey, makes clear its relationship to the melanoeratic ijolites of Madagascar described by Lacroix, and named ‘bekinkinite’ by Rosenbusch. It is considered as a special modification of the Paisley teschenite or dolerite.