Principles of Geology. 1 1 



in rocks, and buried in mountains, far removed from the sea. To 

 find tlie cause of this phenomenon was an object of interest, long 

 before any settled system of geological observation and induction 

 was thought of. The study of organic fossils was prosecuted with 

 various success by different naturalists, but it was reserved for our 

 own times to demonstrate their high importance in elucidating the 

 history of the earth. Undoubtedly it is possible to acquire a com- 

 petent notion of fossil plants and anjmals, without particular reference 

 to geology ; but no one can be a geologist who disregards the natu- 

 ral history of fossils. 



The slightest practical examination of rocks demonstrates that 

 whilst some strata abound with these remains, others contain very 

 few, and some are absolutely void of them. The absence of fossils 

 was once used as a character of the primary rocks, but incorrectly ; 

 for several of the secondary, and all of the independent rocks, are 

 as destitute of fossils as granite and mica slate. Since, then, among 

 the secondary rocks, some contain, and others do not contain, or- 

 ganic remains, they may thus be sometimes distinguished. But 

 when we consider the immense variety of organic remains, and learn 

 that in a very limited district of England, many hundreds of species 

 can be collected, and in the whole kingdom several thousands, it be- 

 comes evident that a more important branch of the inquiry remains : 

 viz. — in what manner the different species are distributed in the in- 

 terior of the earth. Whether, for instance, they are arranged ac- 

 cording to geographical position, as is partly the case with existing 

 races, or according to the order of the different rocks, or mixed con- 

 fusedly together. 



That they are not mixed confusedly together, is decisively proved 

 by many cases like the following : the fossils of the chalk cliffs near 

 Bridlington, are numerous and well known ; so are those of the lias 

 shale in the cliffs near Whitby ; and also those of the mountain lime- 

 stone near Skipton ; and on comparison, it becomes, evident that no 

 one fossil of the whole number is found in two of the strata enumer- 

 ated ! each of these three strata has its own peculiar fossils distinct 

 from those in the others. By prosecution of such comparisons, Mr. 

 Smith discovered that organic fossils are distributed in the earth, not 

 in proportion to depth from the surface, nor even according to chem- 

 ical composition, but according to the order and succession of the 

 rocks. He has the great merit of establishing the facts, 



