Charles Schuchert — Historical Geology, 1818-1918. 47 



Early in the nineteenth century it had become plain 

 that formations of very varying ages were included in 

 each one of the three series. Through the study of the 

 fossils and the recognition of the fact that mountain 

 ranges have been raised at various times, causing 

 younger fossiliferous strata to take on the characters of 

 the Primary, it was seen that these terms of Arduino had 

 lost their original significance. 



The first one to describe in detail a local stratigraphic 

 sequence was Johann Gottlob Lehmann (died 1767). 

 In 1756 he published "one of the classics of geological 

 literature," distinguishing clearly thirty successive sedi- 

 mentary deposits, some of which he said had fossils, but 

 he did not use them to distinguish the strata. 



What Lehmann did for the Permian system, George 

 Christian Fiichsel (1722-1773) did even better for the 

 Triassic of Thuringia, in 1762 and 1773. He pointed out 

 not only the sequence, but also how the gently inclined 

 strata rest upon the older upturned masses of the moun- 

 tains ; also that some formations have only marine fos- 

 sils, while others have only terrestrial forms and thus 

 indicate the proximity of land. The deformed strata he 

 thought had fallen into the hollows within the earth, 

 great caverns that had also consumed much of the 

 oceanic waters and had in so doing greatly lowered 

 the sea-level. It was Fiichsel who first introduced the 

 theory of universal formations, and who defined the term 

 formation, using it as we now do, system or period. 

 Even though Lehmann and Fiichsel snowed that there 

 was a definite order and process in the formation of the 

 earth's crust, their example was barren of followers until 

 the beginning of the eighteenth century. 



Wernerian Geology or Geognosy. — "We come now to 

 the time of Abraham Gottlob Werner (1749-1817), who 

 from 1775 to 1817 was professor of mining and mineral- 

 ogy in the Freiberg Academy of Mines. Geikie, in his 

 most interesting Founders of Geology, says that Werner 

 "bulks far -more largely in the history of geology than 

 any of those with whom up to the present we have been 

 concerned — a man who wielded an enormous author- 

 ity over the mineralogy and geology of his day." 

 "Although he did great service by the precision of his 

 lithological characters and by his insistence on the doc- 

 trine of geological succession, yet as regards geological 



