286 GEOLOGY OF OHIO. 



occur near the base, at, Delaware, Monroeville, etc., fossils of great scientific interest. 

 These concretions are often spherical, are sometimes twelve feet in diameter, and 

 very frequently contain organic nuclei, around which they are formed. These nuclei 

 are either portions of the trunks of large coniferous trees allied to our pines, replaced, 

 particle by particle, by silica, so that their structure can be studied almost as well as 

 that of the recent wood, or large bones. With the exception of some trunks of tree 

 ferns which we have found in the Corniferous limestone of Delaware and Sandusky, 

 these masses of silicified wood are the oldest remains of a land vegetation yet found 

 in the State. The Silurian rocks every where abound with impressions of sea weeds, 

 but not until now had we found proof that there were, in the Devonian age, conti- 

 nental surfaces covered with forests of trees similar in character to and rivaling in 

 magnitude the pines of the present day. 



"The bones contained in these concretions are those of gigantic fishes, larger, more 

 powerful, and more singular in their organization than any of those immortalized by 

 Hugh Miller. These fishes we owe to the industry and acuteness of Mr. Hertzer, and 

 in recognition of that fact I have named the most remarkable one Diniehthys Hert- 

 zeri, or Hertzer's terrible fish. This name will not seem ill-chosen, when I sa)' that 

 the fish that now bears it had a head three feet long by two feet broad, and that his 

 under jaws were more than two feet in length and five inches deep. They are com- 

 . posed of dense bony tissue, and are turned up anteriorly like sled-runners; the ex- 

 tremities of both jaws meeting to form one great triangular tooth, which interlocked 

 with two in the upper jaw seven inches in length and more than three inches wide. 

 It is apparent, from the structure of these jaws, that they could easily embrace in 

 their grasp the body of a man— perhaps a horse — and as they were doubtless moved 

 by muscles of corresponding power, they could crush such a body as we would crack 

 an egg-shell." 



One mile north-west from Delaware, Mr. Nathan Miller struck the 

 black slate, on the west side of the Olentangy, at the depth of twenty-one 

 feet, in digging a well. It may also be seen along a little ravine tribu- 

 tary to the Delaware Run, near Mr. Miller's farm, on the land of C. 0. 

 and G. W. Little. Limestone only is seen in the bed of the run a few 

 rods further west. It is blue and fossiliferous. A short distance still 

 higher up the run the black member (No. 11 of the section taken in the 

 Olentangy at Delaware) is seen in the bed of the same run. 



About a mile and a half below Stratford a little stream comes into the 

 Olentangy from the east, bringing along in freshet time a good many 

 pieces of black slate. About a hundred rods up this little stream the 

 beds of the black slate appear in situ in the tops of the bluffs, the Olen- 

 tangy shale, with its full thickness of about thirty feet, being plainly 

 exposed near its junction with the slate, while in the river the limestone 

 beds of the Upper Corniferous are spread out over a wide surface ex- 

 posure. 



In Liberty township, two and a half miles south of Stratford, the 

 black slate may be seen on the farm of Mr. J. Moorhead, on the west side 



