10 * NOTES ON THE NORTHWEST. 



The country from Platte River to Council Bluffs is thus 

 described by Nicollet [p. 39, et seq.] : — 



" It will be recollected that I have represented the whole 

 bed of clay, divided into two portions by a band of iron- 

 stone, as having a nearly uniform thickness of 200 feet, and 

 tliat it is intermixed with lumps of gypsum and limestone, 

 together with nodules of pyrites ; so that a soil, produced 

 from such materials, could hardly be expected to throw up 

 anything but a meagre vegetation. It is of a character, too, 

 to be so acted upon by atmospheric agents, as to exhibit, by 

 the wear and tear of its superficial portions, every variety 

 of fanciful summits — domes, cupolas, towers, colonnades, 

 &c.; imparting to it a remarkably picturesque appearance, 

 especially when contrasted with the dense vegetation that 

 borders the river, and a narrow slip of prairies crowning the 

 summits of the hills that are seen to extend themselves on 

 either side. 



" The same physical causes, under other circumstances, 

 produce new effects, that add to the beauty and grandeur of 

 the scenery. Thus, the rains furrow and cut through the 

 plastic and seleniferous clay, down to the most resisting 

 limestone, giving rise to a sort of advancing platform, with a 

 perpendicular elevation of from 30 to 40 feet, resembling a 

 succession of long lines of parapets. 



" But I have now reached the proper place to treat of a 

 very interesting phenomenon observed in the midst of this 

 cretaceous group. It manifests itself by the occasional 

 appearance of a dense smoke at the top of some conical 

 hill, or along a line of country bounded by the horizon, so 



bably applied to a ridge, and not to a marsh. So Nicollet has himself ap- 

 plied it on his map to the ridge separating the waters of St. Peter's from 

 those of the Missisippi. 



