Geological Society . 147 



The Rocky Mountains, as far as Mr. Rogers could collect from 

 the information of Mr. Sublette, a person engaged for eleven years 

 in the fur trade, and from the journals of Long and Lewis and 

 Clarke and Nuttal, are Primitive. The eastern chain, called the 

 Black Hills, consists of gneiss, mica slate, and greenstone, with 

 amygdaloid and other volcanic substances. Volcanic mounds are 

 frequently seen on the west of the mountains between the rivers 

 Salmon and Louis ; for the distance of more than forty miles the 

 Columbia river flows between perpendicular cliffs, from two to three 

 hundred feet in height, composed of lava and obsidian. The Mala- 

 dor branch of the Columbia takes its direction through a similar 

 gorge, and thermal springs abound in this part of the country. 



On the various organic remains of North America, a Paper by 

 Dr. Harlan, which first appeared in the Transactions of the Geolo- 

 gical Society of Philadelphia, has been republished in Jameson's 

 Journal. 



A valuable Communication on the Bermudas, with which we have 

 been favoured by Lieutenant Nelson, R.E., has taught us that in 

 explaining the formation of strata our homage is not exclusively due 

 to Neptune, Vulcan, and Pluto, but that iEolus must also be re- 

 garded. 



This cluster of islands consists entirely of coral, of what kinds it 

 is unnecessary to specify here, though the author has bestowed upon 

 this part of the subject a large share of attention. Confining myself 

 to what relates more especially to geological science, I may state the 

 following as the most important conclusions which Lieutenant Nel- 

 son's observations tend to establish: 1. That the coral animal does 

 not build above water. 2. That coral islands now in process of 

 forming may and do attain a considerable height, say 260 feet above 

 the level of the sea, without the assistance of volcanoes, earth- 

 quakes, or any other violent catastrophe. 3. That this height has 

 in Bermuda been attained by a mere accumulation of sand and 

 shells, continually blown up and advancing from the coast into the 

 interior. 4. That drift sand is capable of arranging itself in strata. 

 5. That of the strata so formed some may be consolidated, others 

 unconsolidated, and that the two may alternate. 6. That strata of 

 drifted sand do not present horizontal surfaces. 7. That wind is 

 capable of giving to strata the figure of a dome or saddle, or a waved 

 and contorted appearance, or an arrangement round centres, or a 

 high degree of inclination. 8. That in coral islands bays are ori- 

 ginal indentations, not the effects of subsequent abrasion. 9. That 

 the surface of a country may be diversified by hill and dale, though 

 it has never undergone diluvial action. 10. That under favourable 

 circumstances denudation may be occasioned by wind as well as by 

 water. 11. That the ripple-mark, which Mr. Scrope* ascribes to 

 a vibratory movement of the lower stratum of water, agitated by 

 winds or currents, may also be owing to wind. 12. That crevices 

 or fissures may be the results of contraction or unequal expansion, 



* Proceedings of the Geological Society, No. xxi. 1831. 

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