t 
-. 
* . ae 
Notice of Geological Surveys. 133 
merous salt wells of this state in some cases extend to this forma- 
tion, and in others do not reach it. . : 
9. The ‘coal measures” which succeed this are composed as 
usual of repeated series of limestone, sandstone, shale, iron ore and 
coal, and are particularly described in this Journal by Dr. Hildreth. 
The organic remains are of the common coal plants—Lepido- 
dendra, two feet in diameter, Calamites of great size, and Sigil- 
laria with their bristling spines perfectly preserved and standing 
out in every direction, with numerous ferns. The inclination of. 
the coal measures is east south east, thirty five to forty feet in a 
mile, and the direction north north east, with a thickness in 
Muskingum county of twelve hundred to fourteen hundred feet. 
Between the blue and cliff limestone are the “ great marl stra- 
tum,” one hundred and six feet thick, and the “flinty limestone,” 
well developed in Adams county. The former is blue and stra- 
tified—by the action of frost and weather it becomes lighter col- 
ored, and when dry is almost white. 
“Tt is earthy, highly effervescent, contains few fossils, and is 
traversed by thin layers of reddish slaty limestone, two or three 
inches thick.” ne i Oe 
The “ flinty limestone,” like the “blue,” lies in thin layers in- 
terstratified with marl, but differs from it in color, in fossils, and 
especially in having certain layers filled with silicious matter in 
chemical combination, (not arenaceous, ) has the sharp, conchoidal, 
flinty fracture, and fires with steel; oftentimes very much brok- 
en up in small triangular pieces—in others an excellent building 
stone, and never appears weathered. Cyathophylla and Crinoidea, 
of various forms, and corallines, are observed in a few strata. 
Chert, (or flint ?) in nodules, is found in Indiana and at Cincinnati, 
In the soil, and. they become more numerous as we approach Ad- 
ams county, where they are found in their native bed in this 
formation. 'This suggests the idea that it once extended much 
arther west. ‘ . 
Il. Report of a Geological “Survey of Indiana, 1839, by D. D. 
WEN, 
The examination of this state, though general, has been ox 
tended to almost every one of the old counties, and its geology “i 
80 like that of Ohio, that details in its description may not be ne- 
