lOg GEOLOGICAL RECONNOISSANCE 



disappointments; since ore is only locally and not univer sally distributed 

 through the rock; hence it requires not only a general knowledge of 

 minerals, but special experience in this particular rock formation, to sink 

 a shaft successfully on ore, even though the miner may have surface 

 indications to guide him. 



If the ore should be found in sheets, as in Missouri, the thickness of the 

 lead-bearing rock is not a matter of so much moment; but if it should 

 occur in veins or lodes, then that question assumes importance. 



In the north-west part of Arkansas I did not find, at any one place, 

 more than one hundred feet of the cherty, barren limestone exposed; but 

 this is, probably, not its entire thickness. Jn Searcy county, solid cliffs of 

 more than 200 feet of this rock have been observed. In following vertical 

 veins through this rock, the black shales of Hickory and Sugar creeks will 

 be encountered; in this rock it is not likely that ore will be found in suffi- 

 cient quantities to be profitable to work; but this shale is of no great 

 thickness; 38 feet is the greatest number of feet I have seen exposed, and 

 it is not likely that the whole mass will exceed 50 feet. This passed 

 through, solid limestones will be again entered, in which the veins may 

 also prove productive. 



The chances, then, are favorable for the occurrence of productive lead 

 mines in the north-west part of Arkansas, north of the boundary line of 

 the millstone grit and its underlying shales. This boundary line will be 

 hereafter described, and ultimately indicated by a colored geological map, 

 if the survey be hereafter carried through in detail. 



Near the north-east corner of the State of Arkansas, in Benton county, 

 on Butler creek, black slate, the equivalent of that on Hickory and Sugar 

 creeks, makes its appearance on the hillsides in the barrens, under a low 

 cliff of white sub-crystalline limestone. These cliffs are surmounted by 

 cherty limestone, chert, and cherty sandstone, which underlie the flat 

 woods of Spavinaw, like those between Indian creek and Oliver's prairie, 

 in Missouri, south-west of the Granby lead mines. 



A sulphur spring was reported to me on Butler creek, about five miles 

 east of Maysville; but not until I had passed half a day's travel to the 

 south of it, so that I had no opportunity of testing it. 



Beatty's prairie, north-east of Maysville, is a perfect counterpart of 



Oliver's prairie in Newton county, Missouri; the gently undulating surface, 



fringed, like it, with groves of oak, small hickory, is also dotted with low 



mounds, bearing tofts of rank weeds, and made up of isolated heaps of 



chert gravel. These mounds are so uniform in appearance that they 



convey the idea of an artificial origin. 



In riding over this prairie, about 3 miles from Maysville, the ground 



