THE GEOLOGICAL TIME- SCALE. 1 89 



ception of a time -scale, and a natural order of succession of the 

 several formations. 



The Wernerian classification in this respect was a correct one 

 for the rocks in Northern Germany for which it was constructed. 

 The English scale expressed the facts of sequence, so far as 

 known, for the English rocks, but the attempt to .fit either of 

 them to the facts in North America emphasized their imper- 

 fection. The fundamental error in the Wernerian system was 

 the assumption that the scale of Northern Germany was a uni- 

 versal scale, or, expressed in general terms, that the mineralogical 

 constitution of a rock has any necessary relation to its place in 

 the stratigraphical series. 



The next step of progress in making the geological time- 

 scale arose from the study of fossils. Fossils had been observed 

 and recognized as organic remains for centuries before Lehmann 

 and Cuvier. Lehmann, and he not the first, observed that Primi- 

 tive rocks did not contain fossils, while Secondary- rocks con- 

 tained some, and what are now called Tertiary rocks contained 

 them abundantly. But it was not until fossils were closely 

 studied, their characters examined, and the species compared and 

 classified that their importance was realized. Cuvier and Bron- 

 gniart are generally credited with being the first to establish the 

 scientific importance of fossils. (On the Mineral Geography 

 and Organic Remains of the Neighborhood of Paris, 1808). In 

 1796 Cuvier had called attention to the fact that elephant bones 

 discovered by him in the Paris basin were different from the 

 bones of living species. In thus drawing a distinction between 

 living and extinct animals, as implying present and past groups 

 of living beings, the foundation was laid, not only of Palaeontology, 

 but of the whole field of investigation into the history and evolu- 

 tion of organisms. Cuvier and Brongniart, applying their 

 methods of analysis to the rocks of the Paris basin, succeeded in 

 classifying them into strata, and in defining the separate strati- 

 graphical divisions in terms of the contained fossils. The Paris 

 basin rocks being found to lie above the Cretaceous rocks of 

 France and England, which represent the top member of the 



