190 THE JOURNAL OF GEOLOGY. 



secondary formation of the Lehmann classification, were named 

 Tertiary to indicate their geological importance and their relative 

 position in the geological scale. These naturalists did not, how- 

 ever, perfect the geological classification which their biological 

 studies suggested. 



William Smith in England ("Tabular view," 1790, and in 

 unpublished maps and sections of the first and second decades of 

 this century) emphasized the value of fossils as means of identify- 

 ing strata in different regions, and others had some part in the 

 elaboration of the principle involved, but Lyell more than any one 

 else perfected the scheme of classification of geological forma- 

 tions on the basis of their fossil contents. We find him saying, 

 in the second edition of his Elements of Geology, published in 

 1 84 1, "When engaged in 1828, in preparing my work on the 

 Principles of Geology, I conceived the idea of classing the whole 

 series of Tertiary strata in four groups, and endeavoring to find 

 characters for each, expressive of their different degrees of 

 affinity to the living fauna" (p. 280). A mathematical com- 

 parison was made between the proportionate numbers of recent 

 and of extinct species to the several divisions of the Tertiary 

 rocks of England. The result is given in the following table 

 (copied from his "Elements," 2d Ed., Vol. I, p. 284). 



Period. Locality. 



Post -Pliocene, Freshwater, Thames Valley, 



Newer- Pliocene, Marine Strata near Glasgow, 



Older Pliocene, Norwich Crag, 



Miocene, Suffolk, red and coralline crag, 



Eocene, London and Hampshire, 



In the nomenclature here proposed Eocene is derived from 

 the Greek y/ws, dawn, and KatW, recent ; Miocene from /AetW /catVos, 

 less recent ; Pliocene from irXuov KaLvo<;, more recent, and the 

 definite meaning of the nomenclature and the classification is 

 to signify that the strata called Eocene contain the first traces 

 of the fauna now living, the Miocene strata a small proportion 

 of the living species, the Pliocene and Post -Pliocene more and 

 still more of the living types, and that the whole of the Tertiary 



