EXPEDITION 



FROM 



PITTSBURGH TO THE ROCKY MOUNTAINS. 



CHAPTER I. 



Sandstone formation at the base of the Rocky Mountains — 

 The Platte within the mountains — Granite between the 

 Platte and the Arkansa —Birds — Plants^ &c. 



The inclined sandstone at the base of the Rocky Moun- 

 tains we found much wider and its summits incomparably 

 more elevated than our previous opinions, or a distant view 

 had led us to expect. This extensive range, rising abruptly 

 from the plain, skirts the base of the mountain like a vast 

 rampart, and from a person standing near it, intercepts the 

 view of the still more grand and imposing features of the 

 granite ridge beyond. It consists of rocks in which the com- 

 minuted fragments of primitive aggregates are intermixed 

 with the reliquiae of the animals of a former world, known 

 to us only by the monuments which these remains exhibit. 

 The stratifications, with which this rugged and precipitous 

 wall of sandstone is distinctly seamed, penetrate the mass 

 with various degrees of obliquity; not unfrequently the la- 

 minae are entirely vertical, as if the whole had receded from 

 its original position, and these immense rocky masses, had, by 

 the operation of some powerful agent, bten broken off from 

 their former continuity, with the strata now found in a hori- 

 zontal position in the plains. 



VOL. II. 1 



