284 A CENTURY OF GEOLOGY. 



is afterwards raised above sea level and dissected by rivers. American 

 geologists, on the contrary, are apt to regard such level surfaces as 

 the final result of aerial degradation or a base level of rain and river 

 erosion. The same ditference is seen in the interpretation of glacial 

 phenomena. Until recently English geologists were inclined to attrib- 

 ute more to iceberg; Americans more to land ice. Again, in England 

 coast scenery is apt to be attributed mainly to the ravages of the sea, 

 while in America we attribute more to land erosion combined with 

 subsidence of the coast line. In a word, in the tight little sea-girt 

 island of Great Britain, where the ravages of the sea are ^^early making 

 such serious inroads upon the area of the land, it is natural that the power 

 of the sea should strongly affect the imagination and impress itself 

 on geological theories, and tend, perhaps, to exaggeration of sea agen- 

 cies, while the broad features of the American continent and the evi- 

 dences of prodigious erosion in comparatively recent geological time 

 tend to the exaggeration of erosive agenc}^ of rain and rivers. These 

 two nuist 1)6 duly weighed and each given its right proportion in the 

 work of earth sculpture. 



PALEONTOLOGY. 



Paleontology at first attracted attention mainly by the new and 

 strange life forms which it revealed. It is the interest of a zoological 

 garden. This interest is of course perennial, but can hardly be called 

 scientific. Geology at first was a kind of wonder book. 



Next fossils, especially marine shells, were studied as characteristic 

 forms denoting strata of a particular age. They were coins b}^ which 

 we identify certain periods of history. They were ''medals of crea- 

 tion." It was in this way chiefly that William Smith, the founder of 

 English stratigraphic geology, used them. It was in this way that 

 Lyell and all the older geologists, until the advent of evolution, were 

 chiefi}" interested in them. 



It was Cuvier, the great zoologist and comparative anatomist, who, 

 in the beginning of the present century, first studied fossils, especially 

 mammalian fossils, from the zoological point of view, i. e., as to their 

 affinities with existing animals. Cuvier's studies of the vertebrates of 

 the Paris basin may be said to have laid the foundation of scientific 

 paleontology from this point of view. 



Thenceforward two views of paleontology and two modes of study 

 gradually differentiated from one another — the one zoological, the other 

 geological. In the one case we study fossils in taxonomic groups — 

 i. e., as species, genera, families, orders, etc. — and trace the gradual 

 evolution of each of these from generalized forms to their specialized 

 outcomes, completing, as far as possible, the genetic chain through all 

 time; in the other, we study fossils in faunal groups, as successive 

 geological faunas, and the geographic diversity in each geological 



