Page:A Treatise on Geology, volume 2.djvu/311

 CHAP. X. of Man, and North Wales belong. Now all these axes of elevation range north-east and south-west, and thus appear to support De Beaumont's hypothesis. Professor Sedgwick, in a recent communication to the Geological Society (May, 1838), speaks of the importance of attending to this conformity of direction in the axes of elevation, while attempting to join into one classification, according to geological age, the formations of distinct regions. He states further, in support of the same general views, the probable contemporaneity of the parts of another and later system of dislocations passing east and west in Cornwall, Devon, and South Wales, after the deposition of the coal strata. Lastly, he notices a system of dislocations which have brought up a portion of primary rocks, at Dudley, on both sides of the Coventry coalfield., and in Charnwood forest. At all these localities the "strike" is the same, and the lines of the greatest movement are nearly parallel, all being about N.N.W. and S.S.E.; and all these movements belong to one epoch, having been completed after the deposition of the lower new red sandstone (rothetodteliegende), and before the period of the upper sandstone and gypseous marls. Hence we have three great systems of elevation, which occurred during three distinct geological periods, and range in three distinct geographical directions.

This favourable testimony to the hypothesis of De Beaumont might perhaps be further extended: it is, however, met by the following facts:—

Dislocations almost perfectly parallel to those of Devonshire and South Wales range across the cretaceous and tertiary systems of Hampshire, Dorsetshire, and Sussex. In the counties of Radnor and Brecon, anticlinal axes range N.E. and S.W. through districts where the old red sandstone is conformed to the primary strata; and the same direction is observed extensively in the south-western part of Yorkshire, in anteclinals which cross the upper part of the mountain limestone series.

Here, then, dislocations of very different ages appear