OF ARKANSAS. 45 
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Sandstone, hard and quartzose. 
Variegated shales, including the Terra Sienna earth and segregations 
_of hydraulic (?) limestone, and some mudstone shale interstratified. 
Thin-bedded, light-grey limestone. 
Buhrstone, 6 to 8 feet thick. 
Light-colored magnesian limestone, of silurian date? 
Compact, flinty siliceous rocks. 
J. E. Ware is of opinion, the best quality of buhrstones, of any required 
dimensions, can be obtained either in Camp creek hollow or the ridges 
opposite his flouring mill, on the North Fork, equal in quality to the 
French buhr. . 
Small particles of sulphuret of copper have been picked up by J. E. 
Ware, in the Camp creek hollow, disseminated sparingly in a gangue of 
calc-spar; but no regular vein has, as yet, been detected. 
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Dissty On. oe 
MARION COUNTY. 
The prevailing rocks of this county are varieties of magnesian lime- 
stones, which crop out in terraces and low cliffs on the sides of the hills. 
Some sandstone is intercalated, chiefly towards the upper and lower 
part of the hills. The upper sandstone is of variable thickness, from a 
few inches to 50 or 60 feet. It appears, in many places, as if the under- 
lying magnesian limestone had suffered from irregular denudation; having 
been locally scooped out into deep hollows, into which sand was subse- 
quently swept, and became, afterwards, indurated into a hard, solid rock. 
The lower sandstone I have only had a good opportunity of examining, 
as yet, in the adjacent county of Carroll, on township 20 north, range 18 
west, of the 5th principal meridian, where it has the hard quartzose 
character of the lowest sandstone of Wisconsin and Minnesota, as it 
occurs on the Minnesota, Baraboo, and Wisconsin rivers. 
The upper sandstone is generally overlaid by limestones, capable of 
receiving a good polish. Some of the beds are pink, variegated with 
white, or light grey; others, nearly white, or light grey, and often studded 
with entrochites: that is, the disjointed stems of those singular flower-like 
animals, known by the name of encrinites, which flourished in such pro- 
fusion in the ancient seas, in which the deposits and chemical precipitates 
were accumulating, that produced the so-called silurian, devonian, and 
carboniferous rocks. 1g These contribute greatly to the beauty of the 
marble of which they form a part; appearing, often, of different shades of 
color from the matrix in which they are enclosed, and giving to the rock 
