Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 2.djvu/18

 4 Strata, are represented as occurring on each side of this elevated Granite, which is supposed to have broken through, and to have carried up with it to their present elevated and highly inclined position, strata that were once continuous and nearly horizontal.

The general history of Elevation appears to be, that mountain chains of various extent, and various directions, have been formed at irregular intervals, during the deposition of stratified rocks of every age; and that Granite had, in many cases, acquired a state of solidity before the period of its elevation.

Within the primary Granite, we find other forms of Granitic matter, (a. 9.) which appear to have been intruded in a state of fusion, not only into fissures of the older Granite, but frequently also into the Primary stratified rocks in contact with it, and occasionally into strata of the Transition and Secondary series, (a. 10. a. 11.) these Granitic injections were probably in many cases, contemporaneous with the elevation of the rocks they intersect; they usually assume the Condition of Veins, terminating upwards in small branches; and vary in dimensions, from less than an inch, to an indefinite width. The direction of these veins is very irregular: they sometimes traverse the Primary strata at right angles to their planes of stratification, at other times they are protruded in a direction parallel to these planes, and assume the form of beds. Some of the relations of these Granitic Veins to the rocks intersected by them are represented at the left extremity of the Section, (a. 9.)