512 HISTOEY OF GEOLOGY. 



in 1762, described this stratified structure of the earth far more dis- 

 tinctly than his predecessors, and pointed out, as the consequence of 

 it, that " the same kinds of earths, stones, and minerals, will appear at 

 the surface of the earth in long parallel slips, parallel to the long 

 ridges of mountains ; and so, in fact, we find them." ' 



Michell (as appeared by papers of his which were examined after 

 his death) had made himself acquainted with the series of English 

 strata which thus occur from Cambridge to York ; that is, from the 

 chalk to the coal. These relations of position required that geological 

 maps, to complete the information they conveyed, should be accompa- 

 nied by geological Sections, or imaginary representations of the order 

 and mode of superpositions, as well as of the superficial extent of the 

 strata, as in more recent times has usually been done. The strata, as 

 we travel from the higher to the lower, come from under each other 

 into view ; and this out-cropping, bassetiny, or by whatever other term 

 it is described, is an important feature in their description. 



It was further noticed that these relations of position were combined 

 with other important facts, which irresistibly suggested the notion of a 

 relation in time. This, indeed, was implied in all theories of the earth ; 

 but observations of the facts most require our notice. Steno is asserted 

 by Humboldt 6 to be the first who (in 1669) distinguished between 

 rocks anterior to the existence of plants and animals upon the globe, 

 containing therefore no organic remains ; and rocks super-imposed on 

 these, and full of such remains ; " turbidi maris sedimenta sibi invicem 

 imposita." 



Rouelle is stated by his pupil Desmarest, to have made some addi- 

 tional and important observations. " He saw," it is said, " that the 

 shells which occur in rocks were not the same in all countries ; that 

 certain species occur together, while others do not occur in the same 

 beds ; that there is a constant order in the arrangement of these shells, 

 certain species lying in distinct bands." 7 



Such divisions as these required to be marked by technical names. 

 A distinction was made of Tancienne terre and la nouvelle terre, to 

 which Rouelle added a travaille intermediaire. Rouelle died in 1770, 

 having been known by lectures, not by books. Lehman, in 1756, 

 claims for himself the credit of being the first to observe and describe 

 correctly the structure of stratified countries ; being ignorant, pro- 



6 Phil. Trans. 1760. 6 Essai Geogna&tique. 



T Encyl. Method. Geogr. Phys. torn. i. p. 416, quoted by Fitton as above, p 159 



