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tended to the Sahara, and the steppes of Asia, 

 But the observations which we have been able to 

 collect, suffice to prove that in both worlds, the 

 plains, the steppes, and the desarts, contain a 

 great number of formations of different ages, 

 and that those formations often appear with- 

 out being covered by alluvial deposits. The Ju- 

 ra-limestone, gem-salt, (plains of the Meta and 

 Patagonia) and coal sandstone, are found in the 

 Llanos of South America; the quadersand- 

 stone * (desart between the Arkansas, and the 

 Canadian river ; River Plata), a saliferous soil, 

 beds of coal (declivity of the Alleghanies, 

 banks of the Ohio), and limestone with % trilo- 



* Long. Expedition, Vol. ii, p. 293. The physiognomy 

 of these rocks cut in walls and pyramids, or divided in 

 rhomboid blocks, seems no doubt to characterize the quader- 

 sandstone j but the sandstone of the eastern declivity of the 

 Rocky Mountains, in which the learned traveller Mr. James, 

 found salt-springs (licks) , layers of gypsum, and no coal, 

 (L. c. Vol. ii, p. 397, 404,) appear rather to belong to va- 

 riegated sandstone {bunte sandstein). 



:[ L. c. Vol. i, p. 15. This coal immediately covers, as 

 in Belgium, the grauwacke, or transition-sandstone. 



X L. c, Vol. i, p. 147. In the plains of the Upper Missoury 

 the limestone is immediately covered by a secondary lime- 

 stone Avith turritulles, believed to be jurassic, while a lime- 

 stone with gryphees, rich in lead-ore, and which I should 

 have believed to be still more antient than oolithic limestone 

 and analogous to lias, is, according to Mr. James, (L. c, 

 Vol. ii, p. 412,) placed above the most recent formation of 

 sandstone. Has this superposition been well ascertained & 



