A CENTURY OF GEOLOGY. 553 



In this connection it is interesting to trace the effect of en- 

 vironment on geological reasonings in different countries. Here- 

 tofore, especially in England, what we have called peneplains were 

 usually attributed to marine denudation — i. e., to cutting back of 

 a coast line by constant action of the waves, leaving behind a level 

 submarine plateau, which is afterward 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 degrada- 

 tion or a base level of rain and river erosion. The same differ- 

 ence is seen in the interpretation of glacial phenomena. Until 

 recently, English geologists were inclined to attribute more to ice- 

 berg, Americans more to land ice. Again, in England coast scen- 

 ery is apt to be attributed mainly to the ravages of the sea, while 

 in America we attribute more to land erosion combined with sub- 

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

 island of Great Britain, where the ravages of the sea are yearly 

 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 ex- 

 aggeration of sea agencies, while the broad features of the Ameri- 

 can continent and the evidences of prodigious erosion in compara- 

 tively recent geological time tend to the exaggeration of erosive 

 agency of rain and rivers. These two must be 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. 



ISText fossils, especially marine shells, were studied as character- 

 istic forms denoting strata of a particular age. They were coins 

 by which we identify certain periods of history. They were 

 " medals of creation." 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 chiefly 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. 



VOL. LVI.— 44 



