Page:A Treatise on Geology, volume 1.djvu/211

 CHAP. VI. but for the covering of red sandstone, which conceals the coal along the middle of the basin.

The great South Wales coal field is a vast double trough, having an included anticlinal axis, ranging east and west; as diag. 56. In the Barnstaple and Bideford beds belonging to this system, the principal dislocations range also east and west: this is, perhaps, the most general line of movement in the Somersetshire tracts, where dislocations are numerous and remarkable: it is renewed in the north of France and Belgium (at Mons and Namur), and about Elberfeld. Without now stopping to discuss the bearing of these results on M. de Beaumont's views, we shall observe, that a careful study of the phenomena in the north of England has left but slight doubt on our mind that the application of Mr. Hopkins's mechanical theory (see Cambridge Transactions) to the dislocations of the carboniferous system, will be successful. Mineral veins commonly range a little N. of E. and a little W. of N. in the carboniferous system of the north of England.

We now enter upon the last great member of the palæozoic series of strata—the magnesian limestone—long anked as a part of the new red or saliferous system. In the Encyclopædia Metropolitana (article Geology, 1830, et seq.) I stated, as the result of a general examination of the fossil conchifera of the saliferous