In spite of its remote situation, the Old Red Sandstone of Shetland attracted a considerable amount of attention from geologists during the last century. It is exposed in excellent coast sections, which often yield very beautiful cliff scenery; and, in addition to being the most northerly of the stratified rocks of Great Britain, it includes a rich succession of volcanic and intrusive rocks which are of great interest and variety. The axis or backbone of the Shetland archipelago consists of gneiss, mica schist, slate, and limestone, with epidiorites, serpentine, and talc schists. On each side of this there is an area of Old Red Sandstone; that on the east extending from Sumburgh Head, in the extreme south, to Rovey Head, a little north of Lerwick, and comprising also the islands of Bressay, Noss, and Mousa. On the west side of Shetland the Old Red Sandstone Series is much altered, probably by the heat of the granite and other intrusive rocks, so that they often have the appearance of quartzite, and were for a long time regarded as belonging to the metamorphic series. In 1879, however, Peach and Horne (28) showed that, in places, they contained fossil plants which indicated that they belonged to the Old Red Sandstone formation.