of the mountains, are all elements which determine the total impression characteristic of each district or region. It is true that in every zone the same kinds of rocks, trachyte, basalt, porphyritic schists, and dolomite, form groups having the same physiognomy and aspect. The greenstone precipices of South America and Mexico resemble those of the Fichtel-Gebirge of Germany, just as among animals the form of the Allco, or native race of dogs of the New Continent, corresponds perfectly with that of the European race. For the inorganic crust of the globe shews itself independent of climatic influences; whether it be that differences of climate depending on differences of latitude were more recent than the formation of the rocks, or that the mass of the earth in solidifying and parting with its heat regulated its own temperature,[10] instead of receiving it from without. Thus all the kinds of rock with which we are acquainted may be met with in all parts of the globe, and everywhere affect the same characteristic forms. Everywhere basalt rises in twin mountains and truncated cones; everywhere the porphyritic trap appears in grotesquely arranged masses, and granite in rounded summits. Also similar forms of trees—pines and oaks—adorn the declivities of the mountains of Sweden, and those of the most southern part of Mexico.[11] Yet, notwithstanding these correspondences of form, and this similarity of outline in the component parts of the picture, their grouping gives to the whole the greatest difference of character.
Mineralogy is not more distinct from geology than is the individual description of natural objects from a general
