22 Cincinnati Society of Natural History. 



1. Utica. — The name Eden was proposed by Orton in 

 1873 for a succession of alternating shale and limestone 

 layers comprising about 250 feet of strata at the base of the 

 Cincinnatian series. In 1897, Winchell and Ulrich^ re- 

 placed this term by Utica, believing this formation to be 

 the equivalent of the New York Utica. The five feet of 

 strata at the base of the Eden, as defined by Otron, contain 

 Triarthrus becki, which is characteristic of the New York 

 Utica. The major part of what Winchell and Ulrich called 

 Utica does not contain fossils characteristic of the true 

 Utica, and is no longer correlated with the Utica, but is now 

 known as Eden. The lower five feet of strata are referred 

 by Bassler* to the Utica formation, and given the name 

 Fulton, from the type locality — Fulton, in the East End of 

 Cincinnati. He describes the rocks of the Fulton as "dark 

 gray or drab-colored shales which contrast very distinctly 

 with the overlying Eden shales."^ This formation, which 

 outcrops at 45 to 50 feet above low water of the Ohio at 

 Cincinnati (4v32 ft. A. T.), is the oldest formation of the 

 Cincinnatian. It is underlain by Trenton, the oldest rock 

 outcropping in the Cincinnati region. 



2. Eden. — The Eden at Cincinnati is approximately 230 

 feet thick, and is made up of a series of thin-bedded, cal- 

 careous shales, interrupted at intervals of several feet b}' 

 limestone strata varying in thickness from^ a fraction of an 

 inch to six or eight inches. The formation is characterized 

 by certain fossils which are restricted to it, or which occur 

 abundantly in it. Among these are Climacograptiis typicalis, 

 Heierocrimts heterodaciylus, Callopora onealli sigillarioides, 

 Dalmanella midtisecta, and Plectamhom'tes sericeiis. Besides 



*Orton: Geol. Surv. Ohio, vol. I, pt. I, 1873, p. 372. 



tWinchell and Ulrich: Geol. Nat. Hist. Surv. Minn., vol. 3, pt. 2, 1897. 



tBassler: Proc. U. S. Nat. Mus., vol. 30, No. 1442, 1906, p. 9. 



?Bassler: loc. cit., p. 8. 



IIThe strata outcropping along the Ohio River bank at West Covington, Ft. Thomas, and 

 Pt. Pleasant, which have been usually correlated with the Trenton of New York, have 

 been shown by J. M. Nickles (Ky. Geol. Surv., bull. 5, 1905, p. 18) to be continuous 

 with the Winchester of central Kentucky. He considers them to be of Cincinnatian, 

 rather than Mohawkian age. Bassler (U. S. Nat. Mus. Bull. 92, 1915, pi. 2) however, 

 refers them to the Mohawkian. 



