BUILDING STONE. 6138 
est horizon of the Niagara formation, (a) and are therefore exact equiva- 
lents of the Dayton stone. They are immediately underlaid by the 
Clinton limestones, and the glacial action has plowed away the stones 
of the Springfield and Covington type which once overlaid them. The 
material here extracted is of good quality. The stone lands sometimes 
bring $2,000 per acre near Dayton. Their value is indicated by the cir- 
cumstance that, although the stone is not more than 16 feet in thickness, 
it is frequently extracted in places where 20 feet of dirt and drift must be 
removed from above it. The stone belonging to this horizon is usually 
very strong, specimens having been found to resist a crushing force of 30 
tons on a 2-inch cube. The quarries are situated at and directly south 
of Piqua, upon the west side of the river, with the exception of one 
quarry 23 miles south of the town. ‘The material is sent by rail, canal, 
and team to the neighboring towns and cities of Ohio and Indiana, where 
it is used mostly for rough building purposes. No prominent structures 
have as yet been constructed from it. ‘The thickness of the strata varies, 
and it is therefore possible to obtain slabs suitable for pavements. In- 
deed, it is claimed that slabs 20 feet square from some quarries are 
accessible. The town of Piqua is mostly paved with this stone, utilizing 
for this purpose the poorer and inferior layers. The walks would be 
,greatly improved by the use of the better layers. 
In the quarries immediately at Piqua, about 23 feet of the lowest 
_ layers are heavy and thick, and are used for bridge stones. Then follow 
about 7 feet of building stone, overlaid in one quarry by 1 foot of well 
stone and 2 feet of drift, and in the others there are 7 or 8 feet of Grift 
to be removed. Quarries below the town are overlaid by 22 feet of 
drift, the lower portion of which is composed of fragments of broken 
limestone, of all sizes and shapes, piled together with an intermixture 
of gravel. ‘This stone, like the Dayton stone, is mainly composed of 
calcium carbonate, which, it is said, usually constitutes over 90 per cent. 
of the whole. That it varies, however, between quite wide limits is 
shown by the circumstance that of the two specimens sent on, one is quite 
dolomitic, and will dissolve but little in dilute hydrochloric acid. It 
contains streaks and clear crystalline spots, which are of calcium carbo- 
nate, and under the microscope in minute structure it is found to con- 
tain more or less of sharply-defined crystals, which are probably 
dolomite. The stone in some of its layers contains more or less 
(a) Geological Survey of Ohio, Vol. III, Part i, p. 468: “Geology of Miami County,” by 
John Hussey. 
