130 Notice of G ecological Surveys. 
the surface so much lime as we should anticipate, and rarely, if 
ever, when undisturbed, does it effervesce with acids. On the 
tops of the hills around Cincinnati, the loam lies seven to nine 
feet deep before any stones are mingled with it, and this loam is 
not effervescent with acids. As soon as a layer of stone has been 
passed, all below it is highly so.” By ordinary processes, the 
lime has been undoubtedly removed from the upper part of the 
soil ; “hence the yellow loam near the’ surface is more useful 
for the’ manufacture of bricks that that which comes from be- 
tween the layers of stone; the latter ‘is uniformly effervescent, 
and contains from 12 to 25 per cent. of carbonate of lime.” 
The blue limestone, though classed as a transition rock by Dr. 
Locke, received no particular designation, while Mr. Conrad con- 
siders it as the Trenton limestone of New York, and the equiva- 
lent of the Caradoc sandstone of Murchison.* No specific enu- 
meration of its organic remains is given, although they differ from 
those of the “cliff limestone” as below. There is a series 0 
rocks, eight hundred feet in thickness, between this foundation 
rock and the coal formation of Ohio, and at its point of greatest 
altitude already referred to, it separates the coal basins of Ohio 
and Indiana into two distinct and well characterized formations. 
‘The “cliff limestone,” that lies on the “ blue’ limestone, is 
separated from it as in the section of Adams county, by extensive 
deposits of marl and intermediate limestone, which are much les 
in other places, and is not fissured like the latter, but is entire 
throughout its whole thickness of eighty feet, and where it is cut 
through by the rivers, presents mural bluffs or “ cliffs,” whence 
its name ; or when it forms the bed of the streams it often causes 
cascades and occasions falls, as in the Ohio, at Louisville.  Itis 
less hard and compact than the lower limestone, often soft ana - 
friable like a loose sandstone, and even porous, spongy and arenace- 
ous; of various colors, yellowish, reddish gray, and almost white, 
and is highly fetid and bituminous. * In some places, it is without 
fossils, in others highly. fossiliferous. The organic remains © 
both limestones are marine, and consist of corallines, univalves(?) 
bivalves, and trilobites—sometimes the species are identical in 
both, although generally different. 'The Corallines of the blue 
limestone are small and branched ; those of the “ cliff” are in large 
Paes eee “te ae 
* Vide this Journal, Vol. xxxvii1, p. 87—88. 
* 
