Rocky Mountains. 421 



tem within themselves, having no connexion with the Alle- 

 ghanies or Rocky Mountains. The sandstones which lie 

 about these mountains, abound much more in mica than those 

 near the Rocky Mountains, nearly in the same proportion, as 

 the granite of the latter has less than what is met with in the 

 little we have seen of the former. The Ozark mountains 

 exhibit evidence of metallic riches, far exceeding any thing 

 that appears in the Rocky Mountains. May not an extensive 

 range of granite, and other primitive rocks, have existed at 

 some distant period, where the Ozark inountains now are, 

 containing the vast quantities of the ores of lead, iron, &c. 

 now found in rocks of recent secondary origin, and even in 

 alluvial deposites — and may not the operations of water dur- 

 ing many ages, when an ocean rolled over the summits of 

 these mountains, have worn down those primitive rocks' — 

 their detritus have been deposited horizontally upon their 

 submarine sides and summits, so that the greater part of 

 their surfaces are now covered by secondary aggregates? 



Numerous specimens of minerals, brought by Lieutenant 

 Graham and Dr. Somerville, from the Upper Mississippi 

 and the Illinois rivers, and others from that region, now in 

 the possession of Dr, L. C. Beck, of St. Louis, have a pe- 

 culiar resemblance to similar minerals, met with in the Ozark 

 mountains south of the Missouri. From these resemblances, 

 and from the corroborating testimony of all the accounts we 

 have received concerning that country rich in mines, which 

 lies along the eastern side of the upper Mississippi, we have 

 been induced to believe that a continuation of the Ozark 

 mountains, or at least, of a region similar in mineralogical 

 features, extends from the confluence of the river Missouri 

 northward, to the sources of the Wisconsan, and the 

 Ontonagon of lake Superior. North of the Missouri the 

 country is very little elevated, but aside from this it appears 

 to possess all the peculiar features of the region we have 

 been considering. The sandstones, the limestones and other 

 rocks have a striking resemblance. Both regions abound in 

 the ores of lead, and both afford copper.* We are aware 

 that the great irregularity in the direction of the ridges ac- 

 cessary to this range, and in the dip and inclination of the 

 older secondary rocks belonging to it, may be considered an 

 objection to our idea of the connexion and continuity of the 

 different parts, and the general direction of the group. But 



* Copper has been found in Illinois near the sources of tlie Cache river. 



