214 



THE WONDERS OF GEOLOGY. Lect. III. 



directed attention to the important series of strata now dis- 

 tinguished by the name of Tertiary {see p. 201). The 

 fossil extinct pachyderms, whose bones abound in the 

 gypsum quarries of Montmartre, were by the genius of 

 Cuvier recalled, as it were, into existence, and the philo- 

 sophers of Europe saw with astonishment, whole tribes of 

 unknown and extraordinary types of being, disinterred 

 from rocks and mountains, which had previously been 

 considered as destitute of scientific interest. Analogous 

 strata, some of a marine, and others of a lacustrine and 

 fluviatile character, were soon found to be spread over 

 many parts of the continents of Europe and America ; 

 forming a series so extensive, and requiring such a lapse 

 of time for its production, that the Chalk, hitherto regarded 

 as comparatively of modern origin, is carried back to a 

 period incalculably remote. The tertiary system may be 

 said to constitute a series of strata which unites the 

 present organic kingdoms with the past ; for while the most 

 ancient contain species related to forms that occur in the 

 secondary formations, the most recent insensibly glide into 

 the modern deposits, and abound in fossil remains of recent 

 species of animals and plants, associated with many that 

 are not now known to exist. 



Mr. Lyell has adopted a classification of the tertiary 

 strata, founded on the relative proportion of recent and 

 extinct species of animals, which any given series of beds 

 may contain ; and as shells occur in most of the strata in 

 great abundance, and in good preservation, he has selected 

 these types of animal organization, as the distinctive charac- 

 ters of the principal subdivisions. Though in the present 

 state of our knowledge this method is of great utility, it 

 will probably require considerable modification ; and, per- 

 haps, must hereafter be altogether abandoned; for it cannot 

 be doubted, that strata in which no recent species have yet 

 been found, may yield them to more diligent and extended 



