502 MESOZOIC TIME — REPTILIAN AGE. 



to a mind in the age itself, having in view co-existing species and 

 those that had gone before, is an essential preliminary to a correct 

 apprehension of the life of each epoch. 



5. Disturbances during, and at the close of, the Mesozoic Era. 



In American history we have found evidences of disturbance in 

 the tilted beds of the Connecticut Kiver sandstone and the inter- 

 secting trap, as mentioned on p. 430. The period of the uplift is 

 not ascertained ; but it is evident that it preceded the Cretaceous 

 period, as the Cretaceous rocks are undisturbed and without trap 

 dikes. The destruction of species was complete, as none pass up 

 into the Cretaceous. 



The Cretaceous strata are all concordant in stratification. They 

 indicate oscillations of level in the land and sea, but no violence 

 at any interval during their deposition. 



In Europe, as in America, the Palaeozoic closed amid scenes of 

 great disturbance and metamorphism. But during the progress of 

 the Beptilian age the rocks, Triassic, Jurassic, and Cretaceous, 

 appear to have been laid down for the most part conformably, with 

 few examples of non-concordance, yet with those variations in their 

 distribution that arise from variations of the ocean's level, as a con- 

 sequence of gentle heavings of the earth's crust. There were thus 

 elevations and depressions, producing the varying geography of the 

 age, and successive destructions of species attending them, so that 

 but an extremely small number of Liassic species pass up into the 

 Oolite, — D'Orbigny says none, — and less than a dozen from the Ju- 

 rassic to the Cretaceous ; while the many subordinate epochs also 

 were separated by general destructions, and peopled mostly by in- 

 dependent creations. 



A disturbance took place between the Triassic and Jurassic periods in the 

 region of the Thuringian Forest and the frontiers of Bohemia and Bavaria, the 

 Jurassic beds overlying unconformably the Triassic : it is named by De Beau- 

 mont the System of the Thuringian Forest, and the direction mentioned is N. 50° 

 W. Again, between the Jurassic and Cretaceous was formed De Beaumont's 

 System of the Cote d'Or, having the direction N. 50° E. 



The rocks of the Cretaceous and Jurassic are still very nearly 

 horizontal in the great Anglo-Parisian region (the part of the 

 German Ocean basin exposed to view). 



The close of the Mesozoic era (or that of the Cretaceous period) 

 was a time of disturbance unequalled since the close of the Palaeo- 

 zoic. Its effects are apparent, — 



1. In the destruction of life. — No species, either in Europe or 



