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- 
dried, the following result by chemical analysis: 
