28 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 3 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 clay 10 to 15 feet. 



Light-colored sand and clay, mixed 5 " 



Gravel, cemented by oxide of iron into a conglomerate or 



pudding-stone 3 " 



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 



of leaves 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. 



