OF ARKANSAS. 105 
as most soils of this color proved to be in the analyses of Kentucky soils. 
Water is generally obtained, in these prairies, at the depth of 20 to 25 
feet, after passing through chert and red clay, such as underlies a consid- 
erable area of this county. This underclay will, no doubt, be found an 
excellent fertilizer of land; and entering, as it does, largely into the sub- 
soils of this country, and therefore accessible by subsoiling, will be a per- 
manent store of agricultural wealth to the country. 
‘In the valley of Sugar creek, the black shale is again seen under the 
limestone, and is in view at intervals along this stream, all the way to the 
northern boundary of the state. 
At Squires’ mill, 16 feet of black shale is well exposed, with 6 or 8 inches 
of marly earth between it and the overlying limestone. 
The stripe of the geological formations appears, therefore, to run diag- 
onally through Benton county, from Hickory creek, in the south-east cor- 
ner, to where Sugar creek crosses the state line into Missouri. 
Two and a half miles south of the state line, the limestone, over the 
black slate, contains large Spirifer striatus? 
The succession in Benton county, so far as yet ascertained, is: 
1. Productive and coralline chert, at the head of the Osage and elsewhere. 
2. Cherty limestone of the barren limestone group, forming cliffs on White 
tiver and elsewhere. 
8. Black slate of Hickory and Sugar creeks. 
The first and second members of the preceding section, are of the same 
age and composition as the lead-bearing formations of the Granby lead 
mines, in Newton county, Missouri; and there is every reason to believe, from 
analogy of structure, both in the rocks and general surface of the country, 
that here, in Benton county, as well as in the northern parts of Madison, 
Washington, and western part of Carroll county, discoveries may be made 
of lead deposits, similar to those of the Granby mines, in Missouri; there- 
fore, it may be well, in this connection, to record some of the facts con- 
nected with the mode of occurrence of the lead ores in these mines, which 
is, in many respects, peculiar, and particularly worthy the attention of 
the inhabitants of north-western Arkansas; since it may be the means of 
leading to discoveries that may not only enrich the owner of the land, but 
develop the mineral resources of the country. 
At the Granby lead mines, the lead ore has not generally been found, as 
usual, in fissures and veins, with a more or less perpendicular hade, but 
rather running in horizontal sheets between the stratification of the rocks, 
and generally beneath the great mass of overlying heterogeneous chert 
deposits, where it rests on the underlying limestone, which often possesses 
oolitic structure, close to the rich deposits of sulphuret of lead. 
