394 Expedition to the 



of that magnificent profusion of animal and vegetable life 

 which in other parts of the globe has reared mountains of 

 limestone, clay slate, and those other aggregates which con- 

 sist in a great measure of th^ exuviae of living beings. We 

 shall not here be understood, to contradict an assertion be- 

 fore made, that the sandstones along the base of the Rocky 

 Mountains, contain organic remains, and bear abundant evi- 

 dence of having been, at a comparatively recent period, de- 

 posited gradually from the waters of the ocean. 



The particular which we wish to remark, as distinguish- 

 ing these mountains most strikingly from the AUeghanies, 

 and many other ranges, is the entire want of the aggregates 

 referred by the Wernerians to the transition period; as well 

 as nearly all the stratified primitive rocks, and the more re- 

 cent calcareous formations.* 



This great range as far as hitherto known to us lies near- 

 ly from north to south. Considered topographically, the 

 sandstone formation belongs both to the mountains and the 

 plains; sloping down from the sides of the granite, and dis- 

 appearing under the sands of the Great Desert. The western 

 boundary of this formation of sandstone, appears to be de- 

 fined, and corresponds to the side of the easternmost granitic 

 ranges. From the Platte toward the south, it increases in 

 width, and on the Canadian it extends more than half the 

 distance, from the sources of that river to its confluence with 

 the Arkansa. This sandstone formation we consider as con- 

 sisting essentially of two varieties. 



1st. Red Sandstone. This rock, which appears to be the 

 lowest of the secondary aggregates in this part of the coun- 

 try, is very abundant in all the region immediately contiguous 

 to the Rocky Mountains. We have never met with a stratum 

 entirely similar, in the eastern part of the valley of the Mis- 



* The highly primitive, and, if we may so speak, silicious character of 

 the Rocky Mountains, would seem to discountenance the opinion enter- 

 tained by some, that our continent has emerged from the depths of the 

 ocean, at a period comparatively recent. The organic remains hitherto 

 observed, in the secondary aggregates along the base of those mountains, 

 are mostly of animals supposed to have inhabited the depths of the ocean. 

 But if the granite of the Rocky Mountains has heenjorced up at a recent 

 period, where are the traces of all those older secondary rocks, which 

 should have intervened between it and the horizontal sandstones? If these 

 mouDtainB had formed the shores of that ocean, in which the greater part 

 of our continent was so long immersed after the elevation of the Old 

 World, we should have expected to find along their base the remains of 

 littoral animals, and not of those which inhabited the depths of the ocean. 



