164 LYELL'S ELEMENTS OF GEOLOGY. 



Chronological Classification of Aqueous Rocks. 



past time, or of the earth's history. But this we cannot assert ; 

 but merely know that they each relate to successive periods, 

 during which certain animals and plants, for the most part pecu- 

 liar to that era, flourished, and during which different kinds of 

 sediment were deposited in the space now occupied by Europe. 



If we were disposed, on palseontologieal grounds, to divide the 

 entire fossiliferous series into a few groups, less numerous than 

 those in the above table, and more nearly co-ordinate in value 

 than the sections called primary, secondary, and tertiary, we 

 might, perhaps, adopt the six following groups or periods.* At 

 the same time I may observe, that in the present state of the 

 science, when we have not yet compared the evidence derivable 

 from all classes of fossils, not even those most generally distri- 

 buted, such as shells, corals, and fish, such generalizations are 

 premature, and can only be regarded as conjectural schemes for 

 the founding of large natural groups. 



1 . Tertiary from the Newer Pliocene to the Eocene inclusive. 



2. Cretaceous from the Chalk to the Wealden inclusive. 



3. Oolitic from the Oolite to the Lias inclusive. 



A TT AT o A $ including the Keuper, Muschelkalk, and Bunter 



4. Upper New Red J Sandstein of the Germans. 



5. Lower New Red and ( including Magnesian Limestone (Zechstein), Coal, 



Carboniferous .....'.. ( and Old Red sandstone. 



6. Primary fossiliferous ... j ^S^SS^?^ tOthe WeSt fossiliferous 



The limits of this volume will not allow of a full description, 

 even of the leading features of all the formations enumerated in 

 the above tables ; but I shall briefly advert to each of them in 

 chronological order, as they will afford illustrations of the rules 

 of classification, the tests of relative age, and the mode of deriving 

 information from geological monuments respecting the former 

 history of the earth and its inhabitants. 



Tertiary formations. TJiese strata, as we have seen, were 

 so called because, when first discovered, they were observed to 

 be of a date posterior to the chalk, which had long been regarded 

 as the last or uppermost of the secondary formations. It was 

 remarked, that in France, Italy, Germany, and England, the 

 tertiary deposits occupied a position, in reference to all older 

 rocks, like that of the waters of lakes, inland seas, and gulfs in 

 relation to a continent, being often, like such waters, of great 

 depth, though of limited area, and frequently occurring in de- 

 tached and isolated patches. The strata were for the most part 



* Palaeontology is the science which treats of fossil remains, both animal and 

 vegetable. Elym. ira\aios, palaios, ancient, oira, onto, beings, and Xoyoj, logos, 

 a discourse. 



