Rocky Mountains. 413 



north of the Arkansa Mr. Schoolcraft informs us that 

 granite, gneiss, and mica slate, exist in Missouri, but has 

 omiited to point out the particular localities.* 



At St. Louis, Cote Sans Dcssein, Isle a Loutre, and at 

 many points on the Missouri, the limestone partakes of the 

 character of lioth the varieties above described but is rare- 

 ly if ever so exclusively crystalline, as in the Lead Mine 

 district. Most of the limestones that occur immediately on 

 the banks of the Missouri, between Franklin and Council 

 Bluff, are crystalline, and often of a yellowish or reddish 

 white colour.f 



The horizontal limestone, near the mouth of the Ohio, is 

 of a bluish gray colour, of a compact or fine granular struc- 

 ture, and contains some metallic ores, sometimes occurring 

 in veins, which contain beautifully crystallized fluat of lime. 

 Near some of these localities of fluat of lime, we have ob- 

 served the rock itself to contain small and apparently water- 

 worn masses of hornstone, and some fragments of a perfect- 

 ly white gi annular limestone. 



IL — Petrosilex. 



In the vicinity of Bainbridge, ten miles above Cape 

 Girardeau, is a stratified gray flint rock, having an as- 

 pect and fracture very similar to the common gun flint. 

 This rock is here an extensive stratum, and occurs in con- 

 nexion with compact limestone. In tracing it towards the 

 southwest, we have not been able to detect the slightest in- 

 terruption to its continuity, through an extent of more than 

 two hundred miles, along the central portion of the moun- 

 tamous district. Towards the southwest it is found to acquire 

 gradually a more and more primitive character, and losing 

 near the Chattahooche mountain the accompanying stratum 

 of compact limestone, it appears near the Hot Springs of the 

 Washita, associated with the highly inclined argillite of that 

 district. This rock has not, within the compass of our obser- 

 vation been found to exhibit traces of organic remains. Its 

 colour seems gradually to change according to its age, or at 

 least, with the apparent age of the rocks, associated with it. 

 South of the Arkansa, it is of a yellowish or pearly white col- 

 series. Conybeare and Phillipps, pp. 335,351. The celebrated copper 

 mine of Ecton in Staffordshire, is situated in the limestone of the coal for- 

 mation. Ibid. p. 350. 



* Views of the Lead Mines, p. 92. 

 t Jessup-8 Report. 



