THE PRE-ADAMITE EARTH. 



Synopsis of the Animal Kingdom (exclusive of the Annulata) d-wriny the 

 Tenth Jurassic Period. 



394. The close of this period, which marks the termination of 

 the Jurassic age, is distinctly indicated by numerous dislocations 

 and isolations of the strata, denoting upheavings and depressions 

 in many regions. These phenomena demonstrate the complete 

 separation of the last stages of the Jurassic from the first of the 

 succeeding age. M. Elie de Beaumont considers the catastrophe 

 which raised the mountain systems of the Cote d'Or (215), of 

 Monte Pila, and the Erzgebirge, the prevailing direction of 

 which is W. 40 S. and E. 40 N., as that which terminated the 

 Jurassic age. 



The Cretaceous Age. 



395. The group of strata to which geologists have given the 

 name of the Cretaceous or chalk formation, being deposited upon 

 the Jurassic group, must have been the result of the succeeding 

 geological age. Its stratigraphical limits, as we shall here con- 

 sider it, are the Purbeck beds below, and the Maestricht beds 

 above. Some British geologists, including Sir C. Lyell, place the 

 former as the uppermost strata of the Oolitic formation; while 

 others, including Sir H. de la Beche, give it to the Cretaceous 

 group. By reference to the tabular section (47), it will be seen 

 that the title given to this Cretaceous group must not be under- 

 stood as implying that chalk is the exclusive character of the 

 strata. 



The superior strata of this formation are not present in 

 England, and hence they take their name from Maestricht, 

 where they are most developed. 

 94 



