OF ARKANSAS. 53 



- Small quantities of zinc ore have also been found here, associated with 

 the lead ore at the Sewell diggings. 



Some sandstones are intercalated with the magnesian limestones of 

 this part of Jennings' creek valley. 



The tops of ridges are mostly strewed over with masses of porous chert. 

 In some of the ridges the red marble rock is in place. 



The surface indications of lead ore are frequent. Mr. McCracken, 

 whose farm adjoins the Sewell diggings, found a lump of lead ore, one 

 foot below the surface, in digging the foundation for his chimney, and 

 pieces weighing several pounds on the hill-sides opposite his house, on the 

 northern side of Jennings' creek. In the tops of some of the ridges, the 

 marble rock occurs in the vicinity of Mr. McCracken's, which appears to 

 have generally a reddish cast. 



In the valley through which the road passes up from Mr. McCracken's 

 to the Flippen barrens, chert and buhrstone are very abundant, lying in 

 large blocks on the surface and along the beds of the creeks, rendering 

 the road very rough and disagreeable to travel over. There are also some 

 glady hill-sides where marly and shaly limestones crop out, like those men- 

 tioned as occurring on the road between Yellville and Wood's mill, in this 

 county. 



The bottom lands of Jennings' creek, are of good quality, but they are 

 narrow and limited in extent. 



The high grounds at the Flippen barrens are chiefly composed of chert 

 belonging to the subcarboniferous era, as indicated by the fossils found 

 there, both those collected by the corps and those generously presented by 

 Mr. William B. Flippen. 



Amongst the cliffs adjacent to the west bank of White river, five or six 

 miles from the Flippen barrens, under overhanging ledges of magnesian 

 limestones in the " Rock House," known by the name of Bean's cave, pecu- 

 liar nitre earths have formed in large quantities. 



At this locality there are large quantities of red ferruginous dry nitre 

 earth, above and below the red laminated layers, containing nitre salts, 

 which, if all converted, by the usual process of manufacture, into salt- 

 petre, would yield about 6.2 per cent. The composition of this nitre 

 earth, is shown by the following chemical analyses, made both of the 

 whole earth by digestion with hydrochloric acid and of the saline portion 

 soluble in water, which extract contains the nitre salts convertible into 

 salt-petre. 



One sample of red, ferruginous, dry nitre earth gave, after being air- 

 Iried, the following result by chemical analysis: 



