Geology and Meteorology west of Rocky Mountains. 351 



Art. XII. — Geology and Meteorology west of the Rocky Moun- 

 tains. 



(Communicated by Prof. Amos Eatoiv, of the Rensselaer School.) 



In exhibiting a transverse section across North America, at page 

 59 of 2d Ed. Geological Text Book, I was compelled to admit the 

 word unknown, west of the Rocky Mountains. While I was pre- 

 paring that work, John Ball, Esq., a graduate of Dartmouth College, 

 Counsellor at Law, &c. was my pupil in Natural History. In less than 

 twenty months from the time of his leaving this school, he furnished 

 me with all that is necessary for filling up that blank in the profile. 



I pledge myself for Mr Ball's accuracy, because 1 know him. He 

 is most scrupulously exact in relating scientific truths, and a very 

 accurate observer. I received his last letter, which he wrote to any 

 part of this district, by the Fur Company, via Canada, dated March 

 3d, 1833, at Fort Vancouver, near the mouth of the Oregon, (Co- 

 lumbia river.) 



The geology of the country west of the Rocky Mountains is remark- 

 ably simple and uniform. The general underlying rock is the Red 

 sandstone, which some English geologists call saliferous rock, and 

 which characterizes the red sandstone group of De La Beche. It 

 is the same which contains the salt springs of the western part of the 

 State of New York, and which underlies the basaltic rocks (green- 

 stone trap) of Connecticut and Hudson rivers. It is the same which 

 Dr. Edwin James describes, (See Long's Expedition) as the chief 

 basis rock between the Rocky Mountains and the Mississippi. There- 

 fore the geology of the east and west sides of the Rocky Mountains 

 is remarkably alike. Mr. Ball says, " the Rocky Mountain rises up 

 from the midst as it were of a horizontal sea of red sandstone ; as if 

 some tremendous force had driven it upwards, like an island forced up 

 from the. depths of the ocean." 



Mr. B. agrees with Dr. James, in comparing the Rocky Mountains 

 with Humboldt's description of the Andes ; of which it is probably 

 a continuation. It consists of slaty granite (gneiss) Hornblende rock, 

 talcose slate, and some mica-slate. The talcose slate is probably a 

 continuation of that which contains the gold of Mexico. 



Mr. Ball considers almost the whole country as volcanic, if basal- 

 tic rocks resting on red sandstone are to be considered as volcanic. 

 In numerous localities the red sandstone resembles the half-raelted 



