THE PRE-ADAMITE EARTH. 



so as to leave band after band of the successive deposits eacli 

 uncovered by the other along its NE. border. 



In the Mediterranean basin all the stages are presented, though 

 in an irregular and dislocated state. 



413. The animal kingdom during the Cretaceous age was de- 

 stroyed and reappeared in each of the seven periods. To the 

 terrestrial animals, such as birds, reptiles, and insects, and the 

 marine animals included in the class of fishes, inollusca, echino- 

 dermata, polyparia, foraminifera, and amorphozoa, which pre- 

 viously existed, must be joined for this age cycloid and ctenoid 

 fishes (salmon and perch), and various forms of foraminifera 

 hitherto unknown. This age was also signalised by the prevalence 

 of cirridated brachiopods, bryozoa and testaceous spongiaria. 

 Ammonite shells also, of the most elegant and various forms, 

 abounded, which disappeared for ever after this epoch. 



The presence during the entire Cretaceous age of the same genera 

 and species of animals, from the line to the 56 of latitude on both 

 sides of the world, prove that these regions, so entirely different 

 in their climate at present, had a uniform temperature, proceeding 

 evidently from the neutralising effect of the central heat of the 

 earth, and which temperature was tropical. 



414. Throughout the whole of this age, all that part of the 

 earth to which geological research has been directed, was subject 

 to the same slow and gradual undulations, as have been observed 

 during the human period on the Scandinaviau peninsula and 

 elsewhere. 



On seven different occasions, however, more violent geological 

 perturbations took place, which swept from the earth and seas 

 every living thing ; and after these great catastrophes, when 

 nature was tranquillised, Almighty power once more repeopled 

 the land and the water, clothing the former with new vegetation. 



FIRST CRETACEOUS I'ERIOD. 



415. The great thickness of this stage, amounting at a mean 

 estimate to 8000 feet, or above a mile and a half, shows that the 

 duration of the period must have been considerable. 



The composition of the stage includes the Purbeck beds, Has- 

 tings sand, Weald clay, and lower green sand of De la Beche, the 

 Tilgate and Ashburnham beds of Mantell, and the Wealden or 

 loth group of Lyell. 



The fauna, exclusive of Annulata, is presented in the following 

 table: 



104 



