16 Ancient Drainage of JVorth America^ Sfc, 



especially, above all the rest, a system for mountain ranges. 

 No man can reason luminously about the origin of mountains, or 

 concerning their specific or generic character, to use Mr. Darby's 

 terms, who is not a competent practical geologist. This im- 

 portant branch of American geology, remains yet to be judi- 

 ciously treated of. 



In this paper, the leading features only of this branch will be 

 adverted to. A great portion of this continent is occupied by 

 a central basin, the walls of which are constituted by ranges of 

 mountains lying at great distances from each other. Long's 

 Peak, is 15,000 feet high ; this is the greatest known elevation 

 of the Chippewayan or Rocky mountains. From thence the 

 country slopes eastward. The plains on its east flanks, are 

 about 3000 feet high, being near the medium elevation of the 

 Alleghany mountains, which may be considered the Eastern wall 

 of the basin. At the mouth of the Platte river, we have a re- 

 duced elevation of 680 feet above tide water, corresponding to 

 the elevation at Pittsburgh on the west flank of the Alleghanies. 

 At the mouth of the Ohio, where it joins the Mississippi, the de- 

 pression of the basin, is only equal to 300 feet above tide water. 

 The central line of drainage of this great basin, is occupied by 

 the Mississippi, which receives from its northern and eastern 

 slopes, the Wisconsan, the Illinois, the Ohio, &c. The longest 

 line of drainage is occupied by the Missouri, north and west 

 of the Mississippi, and receives from its western slope, until it 

 joins the Mississippi, the Muddy, the Yellow Stone, and the Platte 

 rivers, and afterwards the Arkansa and its tributaries, the Red 

 river, &c. In about 50° N. lat. another chain of high lands,* 

 connected with the Chippewayan mountains, begins, and runs 

 N. E. between lake Winnipec, and the great Slave lake, of 

 which region it is the water shed. South of this chain, the mean 

 elevation of its table land is about 1200 feet. This chain, which is 

 probably connected with the highlands running north of lakes 

 Superior, Huron, &c. may be regarded as the ancient northern 

 wall of the great basin now described. The table land is full 

 of lakes, many of which have no connection with each other, 

 except in the rainy season, when the Assinaboin and Red river 

 of Hudson's bay, which run north, are said to mingle their wa- 

 ters occasionally with those of St. Peters, which flow southward 



* Accurate details of this region are much wanted. 



