Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 2.djvu/19

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A. 10. represents a dike and protruded mass of Granite, intersecting and overlying stratified rocks of the Primary and Transition series. A. 11. represents the rare case of Granite intersecting Red Sandstone, Oolite, and Chalk.

Closely allied to Granite Veins, is a second series of irregularly injected rocks, composed of Sienite, Porphyry, Serpentine, and Greenstone (b. c. d. e.) which traverse the Primary and Transition formations, and the lower regions of the Secondary strata; not only intersecting them in various directions, but often forming also overlying masses, in places where these veins have terminated by overflowing at the surface, (b'. c'. d'. e'.) The crystalline rocks of this series, present so many modifications of their ingredients, that numerous varieties of Sienite, Porphyry, and Greenstone occur frequently in the products of Eruptions from a single vent.

The scale of our Section admits not of an accurate representation of the relations between many of these intruded rocks, and the strata they intersect; they are all placed, as >br />the representation of the injections of Basaltic and Volcanic matter which the portion of the section is intended to illustrate.