THE SURFACE OF THE GLOBE. 45 



Progress of Mineral Geology. 



In truth, the mineral portion of the great problem of the theory of 

 the earth has been studied with admirable care by Saussure, and 

 brought to a wonderful development by Werner, and by the numerous 

 and talented disciples of his school. 



The former of these celebrated men, scrutinising with indefatigable 

 toil for twenty years the most inaccessible mountainous districts, in a 

 manner attacking the Alps themselves in every direction, in every de- 

 file, has laid open to us all the confusion of the primitive formations, 

 and has clearly traced the secondary formations. The latter, availing 

 himself of the numerous excavations made in countries containing the 

 oldest mines, has fixed the laws relating to the succession of layers ; 

 he has pointed out their relative antiquity, and traced each through its 

 respective change. It is he, and he only, who has given a date to 

 geology, as far as regards the mineral nature of the layers ; but neither 

 Saussure nor Werner have determined the fossilized organized species 

 in each sort of layer, with that necessary exactness which is so requisite, 

 from the prodigious number of known animals which they contain. 



Other men of science, indeed, studied the fossil relics of organized 

 bodies ; they collected and published drawings of them by thousands ; 

 their works will be valuable collections of materials ; but, more en- 

 grossed with animals or plants, considered as such, than with the 

 theory of the earth, or, regarding these petrifactions or fossils as curio- 

 sities rather than historical documents, or, in truth, contenting them- 

 selves with partial explanations on the relative bearing of each relic, 

 they have almost always neglected to seek for the general laws of posi- 

 tion, or the relation of fossils with the layers. 



Importance of Fossils in Geology. 



And yet the idea of such a research was very natural. How was it 

 overlooked that it is to fossils alone that must be attributed the birth 

 of the theory of the earth ; that, without them we could never have 

 surmised that there were successive epochs in the formation of the 

 globe, and a series of different operations ? Indeed, they alone prove 

 that the globe has not always had the same crust, by the certainty of 

 the fact that they must have existed at the surface before they were 

 buried in the depths where they are now found. It is only by analogy 

 that we extend to primitive formations that conclusion which fossils 

 enable us definitively to ascribe to secondary formations ; and if there 

 were only formations without fossils, no one could prove that these 

 formations were not simultaneously produced. 



Again, it is to fossils, small as has been our acquaint*'*''* 3 with 



