Geological Survey of the State of Ohio. 355 
glomerate is a few miles west of Jackson, a distance of more than 
twenty miles east of its termination on the section. Not a ves- 
tige of it is to be seen im situ, even on the highest hills in the 
Vicinity of Chilicothe. 
_ We propose to lay before our readers a description of the prin- 
cipal formations in Ohio, beginning with the oldest rocks and as- 
cending in the series. 
I. Great Limestone Deposit.—This is the equivalent of the 
mountain or carboniferous limestone of Europe. It is first struck 
in Adams county, and extends thence to the western borders of 
the State. It is of a grayish color, with a tinge of blue, and sub- 
crystalline in its texture. It generally occurs in layers, varying 
from a few inches to two feet in thickness, with thin seams of 
shale intervening. From its toughness, it forms a valuable build- 
ing material. Organic remains are profusely scattered throughout 
this deposit. Of Zoophytes, the principal are the Caryophylla, 
Turbinolia, Cyathophyllum, Favosites, and Astrea. Of the Crus- 
tacea, Trilobites and Calymene. Of Mollusca, the Spirifer, Pro- 
ducta, and Terebratula. Of Conehifera, the Melaina, Delphi- 
nula, Planorbis, Orthoceratites, Ammonites, and Turritella. On 
some of this limestone we have noticed ripple marks, which were 
probably contemporaneous with its induration. 
From the appearance of this limestone, it is not unreasonable to 
suppose that the particles composing it were once held in aqueous 
solution, and subsequently deposited in tranquil water along the 
bottom of the ocean. 'This may have been consolidated by sub- 
terranean heat, acting on the mass. This is rendered probable, 
by the ingenious experiments of Sir James Hall. From them we 
derive the following conclusions: that a compressing force equal 
to the weight of 52 atmospheres, or 1700 feet of sea, is sufficient 
for the formation of limestone, if a due degree of heat be applied ; 
that under 86 atmospheres, or about 3000 feet of water, a com- 
plete marble may be formed; and lastly, that, with a pressure of 
173 atmospheres, or 5700 feet, a little more than a mile of sea, 
the carbonate of lime is made to undergo complete fusion, and to 
act powerfully on other earths. These compressions are, com- 
paratively, by no means great. The force of gunpowder, at the 
se estimate, is equal to the weight of 1000 atmospheres.* 
* Edinburgh Rev, vol. 9, P- 27, Art. Sir James Hall on B the Effects of alee and 
Caihetsnor 
