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 Coniferous. — That limestone which, in reports o:, the counties of 

 Sandusky, Seneca, Crawford, and Marion, the writer has design ited "Lower 

 Corniferous," is divisible, on account of strong lithological and palseontolog- 

 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 light 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 occasion- 

 ally a specimen of Cyrtoccras 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 Pavosites, 

 Ccenastroma, Strom atopora, and Cyathophylloids. This belt is met with 

 in Crawford county, and seems to prevail toward the north as far as Erie 

 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 



