12 GEOLOGICAL BIOLOGY. 



dispensable agent for the scientific explanation of any ex- 

 traordinary phenomena. For these reasons inquiry did not 

 reach far into the antiquity of the geological ages. And the 

 first attempts at classification took little or no account of 

 actual time-factors in geology. 



Lehmann's Classification according to Order of Formation. 

 Lehmann * is generally credited with having first proposed a 

 classification of rocks on the basis of the order of their forma- 

 tion, as Primitive, Secondary, and a third class, the modern or 

 superficial rocks made by the deluge or ordinary river action. 

 Lehmann recognized also a direct relation of origin for the 

 Secondary from the Primitive rocks, and thus arose the begin- 

 nings of the geological time-scale. Lehmann described three 

 originally distinct kinds of rocks, or rock formations. The 

 volcanic were separated from the others because having no 

 particular connection with either in origin. The distinction, 

 however, between Primitive and Secondary was fundamental. 

 The Primitive was strictly the original, basal rock formed by 

 crystallization from chemical solution before organisms lived ; 

 and the Secondary rocks were of secondary origin, made out 

 of fragments of the older and always lying above them. In 

 the original classification of Lehmann, Secondary included all 

 the stratified rocks, as we now describe them, and in the 

 classifications for some years following Lehmann the term 

 Secondary was applied, though in a restricted sense. 



Cuvier and Brongniart 's and R6bouPs Contributions. Cuvier 

 and Brongniart f proposed the name Tertiary for the rocks 

 classified as Secondary by Lehmann, but lying above what is 

 now known as the Cretaceous system ; and Quaternary was 

 used by Rboul $ in 1833 for the rocks of superficial position 

 and of glacial or fluviatile origin. Thus the nomencla- 



* J. G. Lehmann, " Versuch einer Geschichte von Floetzgebirgen, etc.," 

 Berlin, 1766 (Kayser), 1756 (Poggendorf). French translation cited by Lyell 

 "Essaid'un Hist. Nat. des Couches de la Terre," 1759. See Lyell, "Princi- 

 ples," vol. i. p. 72, and Conybeare and Phillips, "Geology," p. vi and p. xlii. 

 Johann Gottlob Lehmann died in St. Petersburg, 1767. 



f Cuvier and Brongniart, " Descr. Geol. des Environs de Paris, "ed. 2, 1822, 

 p. 9. 



\ Reboul, "La Geologie de la Periode Quaternaire," 8vo, 1833. Morlot, 

 Bull. Soc. Vaudoise des Sc. Nat., iv. 41, 1854. 



