296 GEOLOGY OF OHIO. 
stone is also somewhat blue, or brown-blue, and hard, near the bottom. 
The bituminous matter which, when very finely disseminated, seems to 
cause the bluish and brownish colors, is stronger near the bottom, but 
the stone remains hard and sonorous. 
Lower Corniferous.—That limestone which, in reports on the counties of 
Sandusky, Seneca, Crawford, and Marion, the writer has design ited “‘Lower 
Corniferous,” is divisible, on account of strong lithological and paleontolog- 
ical differences, into two well-marked members. The upper member, well 
exposed and extensively burned for lime at Delhi, in Delaware county, lies 
immediately below the blue limestone quarried at Delaware, as may be seen — 
by reference to the last foregoing section, and has a thickness of about 
twenty-eight feet. It is of a ight cream color, crystalline or saccharoidal 
texture, quite fossiliferous, and usually seen in,beds of three or four 
inches. It is rather hard and firm under the hammer. It makes a lime 
not purely white, but of the very best quality. When this stone is 
deeply and freshly exposed, it is seen to lie in very heavy layers, and as 
such it would furnish a fine crinoidal marble for architecture. Its most 
conspicuous fossils are brachiopods of the genera Strophomena (?), Atrypa, 
Chonetes, and others, with one or two genera of gasteropods, and oceasion- 
ally a specimen of Cyrtoceras undulatum. There may also be seen in these 
beds different species of Cyathophylloids, trilobite remains, and fish-spines 
and teeth. This member of the Lower Corniferous occupies the position, 
relatively to the Hamilton, of the Corniferous limestone of New York, | 
though it is not possible at present to say it is the equivalent of that 
formation. It would thus be the upper member of the Upper Helderberg 
of that State. It has a thickness of about twenty-eight feet. 
Below the Delhi limestone is a fossiliferous belt of limestone, often of a 
bluish color and bituminous character, ten to fifteen feet thick, character- 
ized by corals in great abundance. In the central part of the county of 
Delaware this belt is chiefly fossiliferous in the lower three or four feet, 
the remainder being rather hard, but of a blue color. The southern part 
of the county, however, seems to be without this bluish and highly coral- 
line member, the Delhi beds coming immediately down on the second 
division of the Lower Corniferous. The corals found here are Favosites, 
Ceernastroma, Stromatopora, and Cyathophylloids. This belt is met with 
in Crawford county, and seems to prevail toward the north as far as Hrie 
county. 
The second division of the Lower Corniferous is a light colored, even- 
bedded, nearly non-fossiliferous, vesicular or compact magnesian lime- 
stone, which makes a good building stone, being easily cut with common 
hammer and chisel, and has a thickness of about thirty feet. It is apt 
