On American Geological History, 417 



standing in palisades along the Hudson, and diversifyino- tLe 

 features of New Jersey and parts of Virginia and North Caroh'na. 

 The trap is a singularly constant attendant on the sandstone 

 and everywhere bears evidence of having been thrown out soon 

 after the deposition of the sandstone, or in connection with the 

 formation of its later beds. Even the small sandstone ref^ion of 

 Southbury in Connecticut, has its trap. 



Thus ended in fire arid violence, and probably in submergence 

 beneath the sea, the quiet plains of the Connecticut valley, where 

 lived, as we now believe, the first birds of creation ; kinds that 

 were nameless, until, some countless ages afterwards, President 

 Hitchcock tracked them out, found evidence that they were no 

 unworthy representatives of the feathered tribe, and gave them 

 and their reptile associates befitting appelations.* 



Such vast regions of eruptions could not have been without 

 eff'usions of hot water and steam, and copious hot springs. And 

 may not these heated waters and vapors, rising through the 

 crystalline rocks below, have brought up the copper ores, that 

 are now distributed, in some places, through the sandstone ? 

 The same cause, too, may have given the prevalent red color to 

 the rock, and produced changes in the adjoining granite. 



After the era of these rocks, there is no other American record 

 during the European Jurassic Period. 



In the next or Cretaceous Period, the seas once more abound 

 in animal life. The position of the cretaceous beds around the 

 Atlantic borders shows that the continent then stood above the 

 sea very much as now, except at a lower level. The Mississippi 

 valley, which, from the Silurian, had generally been the region 

 of deeper waters, was even in cretaceous times occupied to a 

 considerable extent by the sea, — the Mexican Gulf then reachino- 

 far north, even high up the Missouri, and covering also a con- 

 siderable part of Texas and the Rocky Mountain slope. 



An age later, the Cretaceous species had disappeared, and the 

 Mammalian Age (or the Tertiary, its first Period) begins, with a 

 •wholly new Fauna, excepting, according to Professor Tuomey, 

 some half a dozen S2:)ecies, about which however there is much 

 doubt. The continent was not more elevated than in the preced- 



* Mr. J. Deane of G-reenfield was also an early explorer of these tracks, and 

 is now engaged in publishing on the subject, illustrating his memoirs with 

 plates of great beauty and perfection. 



B 



