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Warren County Local History by Dallas Bogan

Boulders At Rock School House And At Other Ohio Locations

Dallas Bogan on 6 September 2004
original article by Dallas Bogan
Return to Index to see a list of other articles by Dallas Bogan

Located on St. Rt. 123, about 2 1/2 miles southeast of Lebanon, at the old Rock Schoolhouse, lies a huge boulder that is described as an "erratic rock," or wandering rock, or sometimes referred to as a lost rock.
In geological terms, an "erratic rock" is described as a portion of "till," which commonly contains rock fragments called erratics. These fragments have been carried far from their source by the great glaciers, the most recent, the Wisconsin, and deposited on rock of different compositions.
Early geologists were puzzled as to just exactly where the boulders came from. They certainly did not fit into the scheme of the current landscape.
As the central part of the United States had no such source, then the granite mountains that run from the northern part of New York through Canada, and to the northern shore of Lake Huron, must have been their origin.
These huge boulders were therefore transported for hundreds of miles by the great glaciers.
In states such as Ohio, Indiana and Illinois, the thickness of till averages about 100 feet. During the great glacial meltings, the landscape was scattered with meltwater streams, which spread the rock waste to make an almost perfectly level surface.
Many rock fragments were composed of such a huge mass that they, rather than being buried, were exposed, such as at Rock Schoolhouse.
Prof. Edward Orton, detailed the first description of Warren County's erratic rock about 1870, in his Geological Survey of Ohio. It is written as such:
"Boulders of northern origin are everywhere distributed thru the county. There are several of unusual sizes and one of them deserves especial notice. It is found three miles to the southeast of Lebanon, and gives the name to the schoolhouse located near which is known thru the township as the Rock Schoolhouse.
"The boulder is composed of gneiss [a coarse-grained granitelike rock formed of layers of feldspar, quartz, mica. etc.] in which rose-colored feldspar is a large element, a composition shared by most of the largest erratics in the region.
"It weathers very rapidly and must have had considerably greater dimensions at an earlier day. It now measures above ground level seventeen feet in length, thirteen in breadth and eight feet in height.
"Examination shows it to be sloping outwards under ground in all directions. It is fair to conclude that at least one-half of it lies buried. Its weight above ground will not fall below 140 tons."
S.S. Scoville, one of the foremost geologists from Warren County, describes the rock in the journal of the Cincinnati Society of Natural History in 1879. His measurements were recorded as quite different from Prof. Orton's.
Dimensions described by Scoville were 21 feet in length, width 16 feet, and height above ground, 8 feet. It would possibly contain 2,744 cubic feet, and at 190 pounds to the cubic foot, the entire weight of this boulder would be 510,720 pounds, or slightly over 255 tons.
Within this belt, Scoville says are found countless rocks from 30 pounds to 40,000 pounds in weight.
As we travel northward through Ohio, we find the erratics more numerous. In Ashland the remains of a huge boulder of granite was found, from which locals had for a period of thirty or forty years quarried for home foundations. Its original dimensions were detailed at 25x15x12 feet, and its weight was estimated at 350 tons.
Near Lodi, in Medina County, were found three syenite boulders. (These formations are similar to granite, but are composed of a smaller crystal material.) These, the largest weighing 85 tons, were believed to have been parts of the same conglomerate as the Ashland boulder.
Just a short distance northeast of Lancaster, in Fairfield County, was located a granite boulder which measured 18 feet in length, 15 feet wide and 12 feet in height.
Another granite boulder was found a mile east of Sidney in Shelby County, which contained about 1,250 cubic feet and weighed 104 tons.
A syenite boulder near South Woodbury, in Morrow County, was measured at 9 feet in length, 8 feet wide, and was supposedly 5 feet above ground.
Another syenite boulder was found one mile east of Wilmington, which was 18 feet in length, 12 feet wide and 10 feet high. Its estimated weight was 200 tons.
Boulders, in some Ohio locations, had been found so thickly assembled that farming was next to impossible until cleaned up.
Between Euclid and East Cleveland rocks were so densely distributed that at a distance they resembled a large flock of sheep.
One rather large belt of boulders was the one in Preble County. The central and eastern portions of the county were so littered with these erratics that twelve hundred, exceeding two feet in diameter, were counted on a single acre. Some of the larger ones were dynamited, while others were buried, and some crushed for road building.
Another such region was in Miami County along the road from Tippecanoe to New Carlisle, where the erratics were used for fence lines. Countless numbers of rocks, which contained fragments of various forms and colors, were found in a belt near Troy. The citizens for garden decorations carried many hundreds away.
In the northern parts of the United States, primarily in New England and Wisconsin, the impressive size and great number of boulders creates a striking character to the landscape.
A boulder at Nottingham, N.H., was estimated to weigh 6,000 tons, while another at Whitingham, Vt., weighed about 3,000 tons.
The great ice sheets have exhibited an impressive performance of their great mobility with respect to the transportation of these large rounded rocks. (I say rounded due to the fact that most are of a round nature.) Such a great force is hardly believable, but, as evidenced by the great boulder at Rock Schoolhouse, we have come to accept the stunning ice movements of the past.
And so, the next time you come across a rather large rounded rock in your yard, or perhaps catch a glimpse of one in a nearby field, think of it and its eminent travels from a place far away to a very distant land, your neighborhood.

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This page created 6 September 2004 and last updated 28 September, 2008
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