630 GEOLOGY OF OHIO. 
not appear to weather out ; in some cases, indeed, the fossil appears to be 
firmer than its surrounding stone. In microscopic structure the stone 
bears the appearance of a fragmental stone, being composed almost 
entirely of fragments of fossils. Im the finer ground mass very perfect 
little rhombohedrons of dolomite are developed, which in number are 
apparently disproportionate to the amount of magnesia contained in the 
stone. Many of the fossils have apparently retained their primitive 
condition, but others have been dissolved away and the forms filled with 
crystalline calcite; and this will perhaps explain the different behavior 
of the fossils in weathering. The stone is somewhat bituminous in 
character, as evinced by the odor emitted when struck. Its gray color 
is pleasing to the eye ; it works easily, and will even assume a good polish. 
Dynamite is used as an explosive to a large extent, any desired 
number of charges being exploded simultaneously by means of electricity. 
Although the common stone for foundations and underpinnings 
used in Columbus is obtained from the quarries, still, during the census 
year, no great amount of building stone was extracted, and no important 
structures were built from the material. ‘The quarries can at any time 
be operated much more extensively, and will produce a superior quality 
of stone for fine construction. 
In the eastern half of Logan county a large island of Corniferous 
limestone occurs, the center of which is covered with shales, but all 
around the edges small quarries have been opened for the purpose of 
obtaining stone both for building purposes and for lime. (a) 
At the present time the only quarries of special importance that are 
located in this district are those which are situated a short distance to 
the northwest of Bellefontaine, and the material which they produce is 
used chiefly for rough work. Although capable of producing excellent 
building material, the more important stone structures in the neighbor- 
hood have been built of materials brought from a greater distance. The 
quarry operations are carried on in a quite primitive manner, and at 
present the lower strata in one quarry are inaccessible, since no means of 
drainage have been supplied, and the quarry is filled with water to a 
depth of from 12 to 15 feet. The top layers of the stone are being 
extracted, although the lower layers are best suited for purposes of 
construction. | 
(a) Report of the Geological Survey of Ohio, Vol. III, Part i, p. 482: “ Geology of Logan County,’’ 
by Franklin C. Hill. 
