Dicotyks {Phdijgonus) compresms, Le Conte. 



These strata, or rather deposits, with the excej^tion of Nos. 6 and 

 10, are exceedingly inconstant. Within two squares from the artesian 

 Avell, No. 3 has diminished on the southward to less than three feet, 

 and 5 and 6 are entirely w\anting ; on the northward it is less than half 

 as thick as at the well, and rests upon yellow clay. The irregularity 

 in thickness of these strata, the disappearance of some in short dis- 

 tances, the appearance of otb.ers not in the series at the well, are evi- 

 dences of the deposits not being subjected to the assorting action of 

 water, and therefore I conclude they were deposited by glaciers and 

 icebergs ; and I prefer to ascribe the deposit, at least the lower seventy- 

 five feet, to glacial action. I think there can be little doubt that the 

 valley of the Scioto, that is that area extending from the left bank of 

 the Olentangy to the right bank of the Scioto, is certainly due to 

 glacial action. At Mr. Little's quarry, in the town of Delaware, 

 about a mile west from the right bank of the Olentangy, and at a 

 slight elevation above the bed of the stream, was found a quartzite 

 bowlder, at the terminus of a great groove which it had ploughed; 

 and in so doing had broken into fragments and displaced many of the 

 upper thin strata of the quarry. This quarry is in the upper portion 

 of the corniferous limestone. Erratic, or drift bowlders, are found 

 throughout the material on which the city of Columbus is built — are 

 found beyond the banks of the Scioto as well as in the valley. 



There is no doubt that the line of drainage of the Olentangy and 

 Scioto, from their entrance into Marion county, the former on the 

 eastern boundary and the latter on the western, to their junction at 

 Columbus, in Franklin county, is due to glacial action ; and that the 

 entire area embraced between them, throughout this distance, was 

 once a single sheet of water, and whilst in this situation the waters 

 did much erosive work. During the subsequent submersion, this 

 " bay " was filled up with eroded material from higher grounds, and 



