Note 6 — Chapter XXIX · THE CARBONIFEROUS VOLCANOES OF ENGLAND

The Whin Sill has been the subject of much discussion, and a good deal of geological literature has been devoted to its consideration. The writings of Trevelyan, Sedgwick, W. Hutton, Phillips and Tate are especially deserving of recognition. The intrusive character of the Sill, maintained by some of these writers, was finally established by the mapping of the Geological Survey, and was discussed and illustrated by Messrs. W. Topley and G. A. Lebour in a paper in the 33rd volume of the Quart. Journ. Geol. Soc. (1877), in which references to the earlier observers will be found. See also Prof. Lebour's Outlines of the Geology of Northumberland, 2nd edit. (1886), p. 92. The petrography of the Whin Sill is fully treated by Mr. Teall in Quart. Journ. Geol. Soc. xl. (1884), p. 640, where a bibliography of the subject is also given.