Note 183 — Chapter XXXIV · THE SYSTEM OF DYKES IN THE TERTIARY VOLCANIC SERIES

This point did not escape the attention of that excellent observer, Berger, in his examination of the dykes in the North of Ireland. We find him expressing himself thus:—"The depth to which the dykes descend is unknown; and after having observed the sections of a great many along the coast in cliffs from 50 to 400 feet in height, I have not been able to ascertain (except in one or two cases) that their sides converge or have a wedgeform tendency" (Trans. Geol. Soc. iii. p. 227).