EROSIONS IN THE GHAUT MOUNTAINS. 119 



4. In Unstralified Rocks chiefly. 



1. DeviTs Gate. — Near the rock Independence, on the Sweet Water, in the 

 Rocky Mountains. Length of the gorge, 900 feet. Height of the walls, 400 feet. 

 Width of the gorge, 105 feet. In granite. — Fremont's First Tour, p. 67, with a 

 drawing; also Fremont's Second Tour, p. 164, with a plate. 



2. The American Falls, on Lewis' Fork of Columbia River. — Width of the river, 

 which is contracted at the falls, 870 feet. From these falls the river runs between 

 walls of trap, with occasional interruptions, to the Dalles, or " trough," of the 

 lower Columbia, 800 miles. 



3. The Dalles, or " trough," and rapids, near the mouth of Columbia River. — The 

 basaltic walls here, although not of great height, are continuous for six miles. 

 Perhaps I ought to consider this example as embraced in the last. — Parkers Ex- 

 ploring Tour, pp. 142 and 318. 



4. The Cascades on the Columbia, 50 miles below the Dcdles, or falls. — The walls 

 are trap, from 100 to 400 feet high, and five miles long. — Parker's Ex. Tour, p. 

 142 and 318. 



5. Gorge on Columbia River, a little below Fort Wallah Wallah. — This gorge in 

 trap, is from two to three miles long, and 300 feet deep. — Parker's Ex. Tour, p. 132. 



6. Pavilion River, which empties into the Columbia a little above Wallah Wal- 

 lah, is walled up with trap some 15 or 20 miles. — Same work, p. 289. 



It seems that the Columbia river and many of its tributaries pass through deep 

 and almost continuous cuts in the hard trap for several hundred miles. The above 

 cases are merely some of the most striking spots. 



7. The Dalles of St. Croix River, in Wisconsin, 30 miles above its mouth. — This 

 gorge in trap, is at least half a mile long, and from 100 to 170 feet deep. — Owen's 

 Report on a Survey of Wisconsin, &c, p. 164, and a beautiful sketch on p. 142. 



8. Gorge and Falls, on Pigeon river, in Wisconsin. — This is near the mouth of 

 the stream, which is 75 feet wide, falls 60 feet, and then pursues its way for 600 

 feet, in a deep trough in trap. — Owen's Rep., p. 405, with a sketch. 



9. Adirondac Pass, in the Mountains of Essex county, New York. — This, as 

 described by Professor Emmons, appears to be an immense gulf in the peculiar 

 granite, or hypersthene rock of that region, whose bottom is filled to a great depth 

 with fragments of rock broken from the walls. Those walls on one side present a 

 perpendicular front 1000 feet high, and three-quarters of a mile long. Professor 

 Emmons thinks that the detritus is 500 feet deep, making the original gulf 1500 

 feet. Whether it was excavated by a river, or by the ocean, producing a purga- 

 tory, his description does not enable us to determine. — Emmons' Report on the 

 Geology of New York, p. 216. 



10. Erosions in trap, in the Ghaut mountains of southern India. — Probably the 

 largest outburst or overflow of trap in the world exists in southern India, extend- 

 ing from latitude 16° to 25°, at least, or nearly 600 miles, and some hundreds of 



