94 Cincinnati Society of Natural History. 



describes the limestone as nearly horizontal ; and he gives 

 also the details of a section across the river from Cincinnati to 

 Newport, illustrating it by a colored plate. 



In 1829 Vanuxem called attention to the resemblance the 

 strata of parts of Ohio, Kentucky and Tennessee bore to rocks 

 occuring at Trenton P'alls, New York,* concluding from the 

 fossils that the rocks of the East and of the West were of ap- 

 proximatel}' the same age. This is the fir.st direct correlation 

 made of the strata about Cincinnati with those of New York. 

 But it was not the last, for since that time many others have 

 instituted similar comparisons. A few of these will be here 

 referred to. 



In 1841 Conrad mentioned the limestone of Cincinnati as 

 the "equivalent or continuation of the black limestone of 

 Trenton Falls,"! the correlation being based upon the fossil 

 contents of the rocks. 



In the following year Hall stated + that there was at New- 

 port, Kentucky, opposite Cincinnati, a green shale occupying 

 the same position, and containing' the same fossils as the Utica 

 Shale of New York ; saying also that the rock below it, "which 

 is seen in place only during low water in the Ohio," is proba- 

 bly the equivalent of the Trenton limestone of New York. 

 This correlation is made upon stratigraphical position. 



Previous to this, and to Conrad's correlation mentioned 

 above, Prof. John Locke|| had given an admirable description 

 of the blue limestone of southwestern Ohio, stating that it 

 was found as far south as Lexington, Kentucky, but that at 

 Frankfort, the Cliff limestone was found. The latter is now 

 known to be of Trenton and not of Niagara age, as Dr. Locke 

 supposed. No comj^arison was made by him with rocks in the 

 eastern vStates. 



In I.S43 Mall published a paper?^ in which lie examined the 

 structure of the rocks along a line from Cleveland to the Mis- 

 sissippi River, in the course of which he referred to the strata 

 in the vicinitv of Cincinnati, and other localities in Ohio and 



■"Ani. Jour. Sci., vol. 16, 1829, page 256. 



fPiflh Aiiniiat Rtporl Geol. Siir. of New York, 1841, page 27. 



JAni. jDiir. Sci., vol 42, 1^42, page 61 



llSecoiid Ann. Repl. Geol. Sur. Ohio, 1838, page 207. 



(* I'rans. Am. Asso. Geol. and Nat., 1843, pages 267-293. 



