Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 2.djvu/16

 2 and to one another, more intelligibly than I have ever seen expressed elsewhere. This original drawing by Mr. Webster has formed the basis of the present enlarged and improved section, into which many important additions have been introduced by the joint suggestions of Mr. Webster and myself. The selection and arrangement of the animals and plants is my own; they have been drawn and engraved (together with a large proportion of the woodcuts) by Mr. J. Fisher, of St. Clements, Oxford.

For facility of reference, I have numbered the principal groups of stratified rocks represented in the section, according to their most usual order of succession; and I have designated by letters the crystalline or unstratified rocks, and the injected masses and dikes, as well as the metallic veins, and lines of fracture, producing dislocations or faults. The crowded condition in which all the Phenomena represented in this section, are set together, does not admit of the use of accurate relative proportions, between the stratified rocks and the intruded masses, veins, and dikes by which they are intersected. The adoption of false proportion is, however, unavoidable in these cases, because the veins and dikes would be invisible, unless expressed on a highly exaggerated scale. The scale of height throughout the whole section is also infinitely greater than that of breadth. The plants and animals also are figured on no uniform scale.

The extent of the different formations represented in this section, taking their average width as they occur in Europe, would occupy a breadth of five or six hundred miles. A scale of heights, at all approaching to this scale of breadth, would render the whole almost invisible. The same cause makes it also impossible to express correctly the effect of valleys of denudation, which are often excavated through strata of one formation into those of another subjacent formation.