424 Expedition to the 



separated by a wide secondary and alluvial valley, from the 

 Rocky Mountains is yet to be determined. This range con- 

 sists of low ridges irregular in direction, rarely rising to an 

 elevation of more than fifteen hundred, or two thousand feet, 

 and consisting principally of secondary rocks. 



The formations are, 



1st, Granite^ at the cove of the Washita. 



2nd, ArgillitCy ranging northeast and southwest from Lit- 

 tle Rock, on the Arkansa to the Hot Springs, and thence to 

 the sources of the Kiamesha. 



3d, TransitioJi* Sandstone. A narrow margin following 

 nearly the same direction on the northwest side of the argil- 

 lite and usually inclining like it to the south or southeast. 



4th, Fl'iJit^ [Petrosilex]. From the Hot Springs northeast 

 to the Mississippi, and usually forming the basis of the Pine 

 lands. 



5th, Limest07ie. Compact and sparry. Distributed in the 

 same direction as the last, but more extensive. 



6th, Argillaceous Sandstone, with extensive beds of coal, 

 and abounding in mines of lead. 



7. Diluvial Deposites. There are many extensive tracts of 

 deep argillaceous or calcareous loam, in other instances a 

 more meager soil has resulted from the disintegration of the 

 sand rock. 



These are the remarks we have been able from observa- 

 tion to make respecting the geology of a part of the United 

 States territory, west of the Mississippi. Relating to that 

 part of the interior of our country which lies northwest of 

 lake Superior, and north of the sources of the Missouri, we 

 have little satisfactory information. From the accurate and 

 intelligent Mackenzie, we are, however, able to collect a few 

 important and interesting particulars. This enterprising 



* Id using the word Transition we follow the example of such as have 

 heretofore written concerning the g-eology of North America, without in- 

 tending to acknowledge an adherence to the exploded, or at least unfash- 

 ionable doctrines of Werner. Notwithstanding Dr. Macculloch, Mr. 

 Greenough, Mr. Kidd, and other eminent English geologists " have 

 brought the most satisfactory proof, that there is no such class as that cal- 

 led transition, by the VVernerians,"* we do not know that the; have in- 

 troduced any word which will in this country so readily be understood to 

 apply to those stratified, incliiied rocks, which formerly constituted that 

 class. 



* See a paper on /amieson's Manual in the Lond. Monthly Review for April 1822 

 p. 386. &c. 



