38 VIEWS OF NATTJEE. 



Weather (Cerro de Buen Tiempo, 2304 toises, or 14,733 

 feet high). Both these conical mountains are regarded as 

 still active volcanoes. Fremont's expedition, which has proved 

 alike useful in reference to botany and geognosy, like- 

 wise collected volcanic products in the Rocky Mountains 

 (as scoriaceous basalt, trachyte, and true obsidian), and 

 discovered an old extinct crater somewhat to the east of Fort 

 Hall (43 2' north lat., and 112 28' west long.), but no traces 

 of any still active volcanoes emitting lava and ashes, were to 

 be met wdth. We must not confound with these the hitherto 

 unexplained phenomenon termed smoking hills, cotes brtilees, 

 and terrains ardens, in the language of the English settlers and 

 the natives who speak French. " Hows of low conical hills," 

 says the accurate observer M. Nicollet, " are almost periodi- 

 cally, and sometimes for two or three years continually, 

 covered with dense black smoke, unaccompanied by any 

 visible flames. This phenomenon is more particularly noticed 

 in the territory of the Upper Missouri, and still nearer to the 

 eastern declivity of the Rocky Mountains, where there is a 

 river named by the natives Mankizitah-watpa, or the river of 

 smoking earth. Scorified pseudo-volcanic products, a kind 

 of porcelain jasper, are found in the vicinity of the smoking 

 hills." 



Since the expedition of Lewis and Clarke an opinion has 

 generally prevailed that the Missouri deposits a true pumice on 

 its banks ; but here white masses of a delicate cellular texture 

 have been mistaken for that substance. Professor Ducatel was 

 of opinion that the phenomenon which is chiefly observed in the 

 chalk formation, was owing to " the decomposition of water by 

 sulphur pyrites and to a re-action on the brown coal floetzes."* 



If before we close these general remarks regarding the 

 configuration of North America we once more cast a glance 

 at those regions which separate the two diverging coast 

 chains from the central chain, we shall find in strong con- 

 trast, on the West, between that central chain and the Cali- 

 forniaii Alps of the Pacific, an arid and uninhabited elevated 

 plateau nearly six thousand feet above the sea ; and in the East, 

 between the Rocky Mountains and the Alleghanies, (whose 

 highest points, Mount Washington and Mount Marcy, rise, 



* Compare Fremont's Report, pp. 164, 184, 187, 193, and 299, with 

 Nicollet's Illustration of the Hydroyraphical Basin of the Upper 

 Mississippi River, 1843, pp. 39-41. 



