426 On American Geological History. 



An epocli of some disturbance between the Lower and Upper 

 Silurian is recognized on both continents. Yet it was less com- 

 plete in the destruction of life on Europe than here, more species 

 there surviving the catastrophe ; and in this country there was 

 but little displacement of the rocks. 



The Silurian and the Devonian Ages each closed in America 

 with no greater revolutions than those minor movements which 

 divided the subordinate periods in those ages. Prof. Hall ob- 

 serves that they blend with one another, and the latter also with, 

 the Carboniferous, and that there is no proof of contemporaneous 

 catastrophes giving them like limits here and in Europe. 



But after the Carboniferous, came the Appalachian revolution, 

 one of the most general periods of catastrophe and metamorphism 

 in the earth's history. Yet in Europe the disturbances were far 

 less general than with us, and occured along at the beginning and 

 end of the Permian Period. 



From this epoch to the close of the Cretaceous, there were no 

 contemporaneous revolutions, as far as we can discover. But the 

 Cretaceous Period terminates in an epoch of catastrophe which 

 was the most universal on record, all foreign Cretaceous species 

 having been exterminated, and all American, with a few doubtful 

 exceptions.* This third general revolution was the prelude to 

 the Mammalian Age. But there is no time to do this subject 

 justice, and I pass on, — merely adding, on account of its interest 

 to those who would understand the first chapter of Genesis, that 

 there is no evidence whatever in Geology, that the earth, after its 

 completion; passed through a chaos and a six day's creation at the 

 epoch immediately preceding man, as Buckland, in the younger 

 days of the science, suggested, on Biblical, not on Geological, 

 ground. No one pretends that there is a fact or hint in Geology 

 to sustain such an idea; on the contrary, it is utterly opposed to it. 



II. The question of the existence of a distinct Cambrian sys- 

 tem is decided adversely by the American records. The Mollusca 

 in all their grand divisions appear in the subdivisions of the Lo- 

 wer as well as Upper Silurian, and the whole is equally and alike 

 the Molluscan or Silurian Age. The term Cambrian, therefore, 

 if used for fossiliferous strata, must be made subordinate to Si- 

 lurian. 



* This catastrophe may not have been violent ; it may have been ages in 

 accomplisliment ; yet it was disastrous to the living tribes over the whole 

 sphere. 



