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Should we group the rocks of Ohio, according
to their lithological characters, we should give five distinct divisions.
They are marked by difference in appearance, hardness, color and composition:
1—Limestone.
2—Black shale.
3—Fine-grained sandstone.
4—Conglomerate.
5—Coal series.
They are all stratified and sedimentary. They are nearly horizontal.
The lowest one visible, in a physical as well as a geological sense, is
"blue limestone."
The bed of the Ohio River near Cincinnati is 133 feet below the level
of Lake Erie. The strata incline in all directions from the southwestern
angle of the State. In Scioto County may be seen the outcropping edges
of all these rocks. They sink at this point in the direction south 80
1/2° east; easterly at the rate of 37 4/10 feet per mile. The cliff
limestone, the upper stratum of the limestone deposit, is 600 feet above
the river at Cincinnati; at West Union, in Adams County, it is only 350
feet above the same level.
The finely grained sandstone found on the summit of the hills east of
Brush Creek and west of the Scioto sinks to the base of the hills, and
appears beneath the conglomerate, near the Little Scioto. Although the
rock formations are the same in all parts of the State, in the same order,
their thickness, mass and dip, are quite different.
Chillicothe, Reynoldsburg. Mansfield, Newburg, Waverly and Rockville,
are situated near the western border of the "fine-grained limestone."
Its outcrop forms a continuous and crooked line from the Ohio River to
Lake Erie. In the southwest portion of the State is the "blue limestone"
occupying a circular
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space from West Union via Dayton, to the State line. The
conglomerate is to the east of the given towns, bending around from Cuyahoga
Falls to Burton, in Geauga County, and then eastward into Pennsylvania.
Near this outcrop are the coal-bearing rocks which occupy the east and southeastern
portions of Ohio. From Rockville to Chillicothe, the course is north, about
10° east, and nearly corresponds with the line of outcrop of the fine-grained
sandstone for an equal distance. The dip at Rockville, given by Charles
Whittlesey, is 80 1/2°, almost at a right angle, and at the rate of
37 feet per mile.
At Chillicothe, the other end of the line, the general dip is south 70°
east, 30 feet to the mile, the line curving eastward and the dip line
to the southward. This is the universal law.
The northern boundary of the great coal fields passes through Meadville,
in Pennsylvania, and turning south arrives at Portage Summit, on the summit
of the Alleghanies, 2,500 feet above the ocean level. It then plunges
rapidly to the westward. From the Alleghanies to the southwest, through
Pennsylvania, Virginia and Tennessee, sweeps this great coal basin.
Much of the county of Medina is conglomerate upon the surface, but the
streams, especially the South Branch of the Rocky River, set through this
surface stratum, and reach the fine-grained sandstone. This is the case
with Rocky, Chagrin, Cuyahoga and Grand Rivers—also Conneaut and
Ashtabula Creeks. This sandstone and the shale extend up the narrow valleys
of these streams and their tributaries. Between these strata is a mass
of coarse-grained sandstone, without pebbles, which furnishes the grindstones
for which Ohio is noted. In Lorain County, the coarse sandstone grit nearly
displaces the fine-grained sandstone and red shale, thickening at Elyria
to the black shale. South of this point, the grindstone grit, red shale
and ash-colored shale vary in thickness. The town of Chillicothe, the
village of Newburg, and a point in the west line of Crawford County, are
all situated on the "black shale."
Dr. Locke gives the dip, at Montgomery and Miami Counties, at north 14°,
east, six feet to the mile; at Columbus, Whitelesey gives it, 81°
52' east, 22 73/100 feet to the mile. The fine-grained sandstone at Newburg
is not over eighty feet in thickness; at Jacktown and Reynoldsburg, 500;
at Waverly 250 to 300 feet, and at Brush Creek, Adams County, 343 feet.
The black shale is 251 feet thick at Brush Creek; at Alum Creek, 250 to
300 feet thick; in Crawford County, about 250 feet thick. The conglomerate
in Jackson County is 200 feet thick; at Cuyahoga Falls, 100 to 120 feet;
at Burton, Geauga County, 300 feet. The great limestone formation is divided
into several numbers. At Cincinnati, at the bed of the river, there is:
1—A blue limestone and slaty marlite.
2—Dun-colored marl and layers of lime rock.
3—Blue marl and layers of blue limestone.
4—Marl and bands of limestone, with immense numbers of shells at
the surface. |
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In Adams County, the detailed section is thus:
1—Blue limestone and marl.
2—Blue marl.
3—Flinty limestone.
4—Blue marl.
5—Cliff limestone.
The coal-fields of Ohio are composed of alternate beds of coarse-grained
sandstone, clay shales, layers of ironstone, thin beds of limestone and
numerous strata of coal. The coal region abounds in iron. From Jacktown
to Concord, in Muskingum County, there are eight beds of coal, and seven
strata of limestone. The distance between these two points is forty-two
miles. From Freedom, in Portage County, to Poland, in Trumbull County,
a distance of thirty-five miles, there are five distinct strata. Among
them are distributed thin beds of limestone, and many beds of iron ore.
The greater mass of coal and iron measures is composed of sandstone and
shale. The beds of sandstone are from ten to twenty or eighty feet thick.
Of shale, five to fifty feet thick. The strata of coal and iron are comparatively
thin. A stratum of coal three feet thick can be worked :o advantage. One
four feet thick is called a good mine, few of them averaging five. Coal
strata are found from six to ten and eleven feet. There are four beds
of coal, and three of limestone, in Lawrence and Scioto Counties. There
are also eight beds of ore, and new ones are constantly being discovered.
The ore is from four to twelve inches thick, occasionally being two feet.
The calcareous ore rests upon the second bed of limestone, from the bottom,
and is very rich.
The most prominent fossils are trees, plants and stems of the coal-bearing
rocks, shells and corals and crustaceae of the limestone, and the timber,
leaves and dirt-beds of the "drift"—the earthy covering
of the rocks, which varies from nothing to '200 feet. Bowlders, or "lost
rocks," are strewn over the State. They are evidently transported
from some remote section, being fragments of primitive rock, granite,
gneiss and hornblende rock, which do not exist in Ohio, nor within 400
miles of the State, in any direction. In the Lake Superior region we find
similar specimens.
The superficial deposits of Ohio are arranged into four geological formations:
1—The ancient drift, resting upon the rocks of the State.
2—The Lake Erie marl and sand deposits.
3—The drift occupying the valleys of large streams, such as the
Great Miami, the Ohio and Scioto.
4—The bowlders.
The ancient drift of Ohio is meager in shell deposits. It is not, therefore,
decided whether it be of salt-water origin or fresh water.
It has, at the bottom, blue clay, with gravel-stones of primitive or
sedimentary rocks, containing carbonate of lime. The yellow clay is found
second. Above that, sand and gravel, less stratified, containing more
pebbles of the |
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sedimentary rocks, such as limestone and stone, iron ore,
coal and shale. The lower layer contains logs, trees, leaves, sticks and
vines.
The Lake Erie section, or "Lake Erie deposits," may be classed
in the following order :
1—From the lake level upward, fine, blue, marly sand—forty-five
to sixty feet.
2—Coarse, gray, water-washed sand—ten to twenty feet.
3—Coarse sand and gravel, not well stratified, to surface—twenty
to fifty feet.
Stratum first dissolves in water. It contains carbonate of lime, magnesia,
iron, alumina, silex, sulphur, and some decomposed leaves, plants and
sticks. Some pebbles are found. In contact with the water, quicksand is
formed.
The Hickory Plains, at the forks of the Great Miami and White Water,
and also between Kilgore's Mill and New Richmond, are the results of heavy
diluvial currents.
In presenting these formations of the State, we have quoted from the
experience and conclusions of Charles Whittlesey, eminent as a geologist,
and who was a member of the Ohio Geological Corps. |