20 GEOLOGICAL BIOLOGY. 



ciple, but many of the divisions here recorded are still re- 

 tained. This latter fact we may interpret to mean that dis- 

 tinctions based upon mineral or lithological characters are of 

 some real and permanent value in geological classification. 

 The history of development of this system from the first, or 

 Lehmann's system, shows that the linear order of the series 

 of formations in the list is based on the conception of a time- 

 scale and a natural order of succession of the several forma- 

 tions. 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 imperfection. The fundamental error in 

 the Wernerian system was the assumption that the scale of 

 Northern Germany was a universal scale, or, expressed in 

 general terms, that the mineralogical constitution of a rock 

 bears some necessary relation to its place in the stratigraph- 

 ical series. 



Fossils substituted for Minerals in classifying Stratified 

 Rocks. — 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 Primitive rocks did not contain fossils, while 

 Secondary rocks contained 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 Brongniart. — Cuvier and Brongniart are gener- 

 ally credited with being the first to establish the scientific 

 importance of fossils.* 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 



* "On the Mineral Geography and Organic Remains of the Neighborhood of 

 Paris," 1808. 



