Page:A Treatise on Geology, volume 1.djvu/293

 CHAP. VI. Wight, is nearly parallel to the south coast of England. Thus the lines would converge toward the east somewhere about Boulogne; and diverge westwards, so that, if continuous (which they are not), the northern one would nearly coincide with the south side of the South Wales coal field, and the southern one pass across the southern part of Devonshire. Each of these two lines of dislocation has caused the strata to dip with great steepness to the north (in the Isle of Wight, the beds on this dip are vertical), but the southward dip is in each case moderate. A cross section gives the following appearance:—

To disturbances during the tertiary periods, M. de Beaumont ascribes the elevation on a north and south line of the ridges of high land in Corsica and Sardinia: the Western Alps (from the Mediterranean to Mont Blanc) are considered to have been raised after the deposition of the Swiss molasse, in a direction N.N.E. and S.S.W.; and the principal chain of the Alps, from the Valais into Austria, E. ¼ N. E., to be of so recent a date as to have succeeded all the true tertiary deposits, and to have coincided with the dispersion of the great blocks and masses of diluvium on both slopes of the Alps.

Igneous rocks are no where in England associated with the tertiary strata; but in many parts of Europe, as in Central France, the north and south of Italy, Sicily, on the Rhine and in Hungary, volcanic phenomena are even specially abundant among lacustrine tertiaries.

From the activity of Etna and Vesuvius, we pass by