OF CREATION. 183 



CHAPTER IX. 



THE GIGANTIC LAND REPTILES, THE FLYING REPTILES, AND OTHER 

 ANIMALS CHARACTERISTIC OF THE OOLITIC AND WEALDEN FOR- 

 MATIONS. 



AFTER the termination of that great deposit of 

 calcareous mud, so characteristic of the older part 

 of the middle secondary period, considerable change 

 seems to have taken place in the relative position of 

 land and sea ; and, from the abundance of calcare- 

 ous rock afterwards developed, as well as from the 

 nature of the fossils, it may safely be concluded that 

 these changes involved important alterations in the 

 whole system of organic nature in this part of the 

 world. Referring only to those districts which, being 

 now land, enable us to discover their structure, and 

 drawing our conclusions only from the actual facts 

 that have been determined, we may venture to con- 

 clude, that, immediately after the deposit of the lias, 

 the bed of the sea was affected by widely acting 

 earthquake movements, and that tracts of land, more 

 or less extensive, rose up, especially on the north- 

 eastern flank of the lias in Yorkshire, in several dis- 

 tricts on the continent of Europe, and in the central 

 and eastern portions of North America. 



It also appears that these elevations must have 

 alternated with depressions, and that thus a number 

 of islands were formed in a sea of moderate depth, 



