98 GEOLOGICAL RECONNOISSANCE 
who, in fact, never visited the country, but plotted the boundary of that 
formation from what they imagined its probable bearings would be through 
Arkansas. 
Between Gainsville and Walcott, a distance of 13 miles, the country is 
mostly a succession of oak and pine ridges, forming a continuation of 
Crowley’s ridge, to the south. 
On the small Colton map of Arkansas, the Walcott post-office is laid 
down 8 miles too far to the north, and Crowley 5 miles too far south. 
The bluff below Dr. Mellon’s house, Walcott post-office, is composed of 
the following materials: 
Red ferruginous tenacious clays +++es steerer eee e eee eee 10 to 15 feet. 
Light-colored sand and clay, mixed. ++ +--+ ++ seers eee ei eee 5. 
Gravel, cemented by oxide of iron into a conglomerate or 
pudding-stone Bh iuikl Brecon eee “BEA arbiters eas srw lee: wi ace ar aS BIG Saige i ee 
White, quartzose, fine-grained sand, with streaks of yellow 
and black sand, running irregularly through it----.+.--- 5 & 
Indurated sandy shale, with pink and yellow streaks--.--- 14 « 
“Hard pan;” indurated dark-grey shale, with impressions 
OE. TRG di cute aca acle ag ode Ae oa arses ati soya b saat acing ouside: team orcas) Buenas noe 1 foot. 
It is probable that the post-oak soil of the Cache flats is derived from 
the disintegration of the indurated sandy shale, reposing on the impervious 
“hard-pan.” 
Clover does not succeed well in this part of Greene county; not even 
on the “black-sand lands.” Herd’s grass and timothy do much better, and 
oats and rye grow very finely —especially on the “ black-sand land.” 
This variety of soil seems, also, peculiarly well adapted to the growth of 
the peach-tree, which comes to perfection very rapidly. It produces both 
a very large and sweet peach. 
‘Wheat succeeds best on the ridge-land; it runs too much to straw in 
the “ black-sand land.” 
On section 10, township 17 north, range 4 east, near Sugar creek, in 
Greene county, there is a remarkable protrusion of hard quartzose sand- 
stone through the quaternary deposits. This sandstone has all the litho- 
logical character of the Potsdam, or lowest sandstone of silurian date, as 
it occurs on the Minnesota and Wisconsin rivers in the north-west. It 
forms a hill of considerable elevation; which, however, I had no opportu- 
nity of measuring, as I examined it in the midst of that most severe 
thunderstorm, accompanied by heavy rain and high wind, which occurred 
on the 7th of November, 1857, in that part of Arkansas. I would estimate 
the height, by the eye, at 100 to 110 feet above the general drainage of 
the country. 
