112 GEOLOGICAL RECONNOISSANCE 
iron ore of the limonite variety of mineralogists was discovered towards 
the base of the sandstone formation—the first member of the preceding 
section. Most of this ore seen on the surface, in connection «with the 
sandstones, was too siliceous to make good iron; but it is not improbable, 
that better ore may be found amongst the underlying shales of the second 
member; strata which, being argillaceous in their composition, are more 
favorable for the retention of segregated iron ore, free from sand. These 
shales, seen in the slope of the road leading to the ford on White river, 
at the mouth of Brush creek, have a ferruginous appearance, favorable 
for the presence of ores of iron. 
Fhe seil east of the Missouri road is more sandy than that west, in con- 
sequence of having received debris and washings from the adjacent main 
sandstone ridge lying to the east. 
It is not improbable, when the highest points of this range of hills come 
to be explored in detail, that some of the members of the upper subcar- 
boniferous group may be found, or even part of the millstone grit series. 
Where chert materials prevail, harder and more durable than the rest of 
the formation, they have resisted decomposition for a longer period of 
time than the surrounding parts, and given rise to those isolated mounds 
whichrise conspicuously, in all directions, out of the prairie, when viewed 
from some elevated position in the neighboring hills. 
The low ridges bordering the northern limits of township 18 north, 
range 29 and 30 west, are composed of chert—the third member of the 
section previously given—while the farming lands in the valleys, which 
join them on the south, are based on the calcareo-siliceous member; i. e. 
the barren limestone formation. The low ridges, 140 feet above the Clear 
fork and the black-jack barrens, in the centre of township 17 north, range 
30 west, adjacent to the Fayetteville road, are of the same formation. 
Near the line between township 16 and 17 north, range 30 west, sand- 
stone ledges, belonging to the first division of the section, are in place, 
resting on the underlying ferruginous shale. In the latter, some iron ore 
was observed. 
Approaching the town of Fayetteville, these strata dip rapidly under 
the upper members of the subcarboniferous group. 
Immediately adjacent to Fayetteville, on the north, ferruginous shales 
are seen, dipping at an angle of 20 deg. to the south-west, underlaid by 
a kind of amygdaloidal sandstone belonging to the millstone grit series. 
One mile west of Fayetteville, on the head of the Trace branch of Wild 
Cat creek, black shale is exposed, containing abundance of good carbo- 
nate of iron, which, with other localities, will go far towards supplying 
the wants of a furnace for the reduction of iron. Over the black shale, 
