14 PHYSIOGNOMY OF PLANTS. 



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 Eichtel-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 Euro- 

 pean 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, ( lft ) 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. Every- 

 where basalt rises in twin mountains and truncated cones ; 

 everywhere the porphyritic trap appears in grotesquely ar- 

 ranged 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. ( n ) 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 



