356 BakeweWs Introduction to Geology. 



ternal shell may probably admit of considerable variation, 

 under a change of circumstances. In attempting to ascertain 

 the identity of distant strata, we ought to bear in mind that 

 there is another circumstance, independently of climate, that 

 may have occasioned the same stratum to have been the 

 abode or sepulchre of very different orders of animals. The 

 depth of the ocean may have varied very much even in con- 

 tiguous situations ; and, in distant countries, the difference of 

 depth may have been very great, and one part might support 

 genera of pelagian animals (or those which live in deep seas), 

 while a more shallow part might be tenanted by different 

 genera or even orders of animals, whose organisation fitted 

 them for moving nearer the surface of the water." Some 

 naturalists seem delighted with forming new species from 

 every slight variation in the form of the shell, and boldly 

 pronounce, from such uncertain data, that fossil shells are 

 different from existing species ; this Mr. Bakewell thinks " to 

 be not more wise, than it would be to class individual men as 

 belonging to different species, on account of the different forms 

 of their noses." 



The remarkable fact, that no vestiges of human remains 

 have been discovered with those of the more ancient inhabit- 

 ants of the globe, is at present fully confirmed; nor have any 

 fossil bones of monkeys been hitherto found. Our author, 

 however, observes, that the vast diluvial beds of gravel and 

 clay, and the upper strata in Asia, have not yet been scienti- 

 fically explored, and both sacred and profane writers agree in 

 regarding the temperate regions of that continent as the cradle 

 of the human race. 



Chapter 3., On the Mineral Substances that compose the 

 Crust of the Globe, is nearly the same as in the former edition. 

 Chapter 4., On the Principles of Stratification, is new and im- 

 portant. Every one who travels through a country for the first 

 time, thinks himself competent to discover at one glance the 

 direction and arrangement of the strata ; but Mr. Bakewell ob- 

 serves, that it is often extremely difficult to trace the stratifica- 

 tion correctly, and that many geologists who have enjoyed a 

 high reputation, appear to have had very imperfect notions of 

 stratification. M. D'Aubuison, in his Traite de Geognoste, 

 published in 1819, has given examples of stratification which 

 never did, nor ever could, occur in nature. 



The curved stratification of the calcareous mountains of 

 the Alps and Jura, and the optical illusions to which they 

 give rise, are particularly described by Mr. Bakewell, and ex- 

 plained by diagrams. 



