A. M. Miller — Ordovician Cynthiana Formation. 653 



shale 4-5 feet thick, and known as the "Fulton" (because it 

 has Triarthus becki, it has been correlated with the Utica), 

 actually belongs about 10 feet above the base of the Eden as 

 identified by the latter. 



It is also now evident that Professor Foerste in his classifi- 

 cation of the Ordovician rocks of Ohio and Indiana* agrees 

 with Ulrich in placing the Fulton immediately above these 

 crinoidal layers. At the same time he expresses doubt 

 as to these 4-5 feet of shale with Triarthus becki being the 

 equivalent of the whole of the Utica further north, in which 

 view the writer concurs. 



The difference for mapping purposes is not appreciable if 

 this lower 10 feet of the Eden be included in the Cynthiana. 

 They appear however to the writer, on account of the frag- 

 mental condition of the contained Eden fossils {Plectambonites 

 rugosus and Ectenocrinus simplex), to have been formed by 

 the working over of basal beds already laid down at the begin- 

 ing of a new cycle of deposition, and to belong properly on the 

 Eden side of the hiatus which everywhere in North Central Ken- 

 tucky marks the juncture of the Cynthiana and Eden. We 

 should place therefore only the lower 40 feet of the limestone 

 beneath the " wave layers " as exposed at Cincinnati and 

 Covington definitely in the Cynthiana. 



Further up the Ohio River from Cincinnati, at Point 

 Pleasant on the Ohio side, and on the Kentucky side opposite 

 New Richmond and Moscow, and at Carntovvn and Foster, 

 Kv,, a greater thickness of beds is exposed below the Fulton 

 shale than at Cincinnati, — seeming to indicate that the axis of 

 the Cincinnati Anticline is trenched by the Ohio River east of 

 Cincinnati. Professor Ulrich would explain the phenomenon 

 by the trenching of the eastward flank of a northward plung- 

 ing anticline at a point further south, due to the general north- 

 ward course of the Ohio River in this stretch. The observa- 

 tions of the writer, however, indicate that the northward 

 plunge of the anticline is too gentle to admit of this explanation. 



At Point Pleasant, Professor Foerste begins the Fulton 

 shale 113 feet above the river. In some places where the 

 lower layers are exposed they contain the brachiopod Dalrna- 

 nella bassleri and the bryozoan Prasopora simulatrix, which 

 indicate the Wilmore bed of the Lexington (Trenton) limestone. 



There is an unexposed interval in all these sections between 

 the Lexington limestone and some distance up in the Cynthiana ; 

 so it is impossible to say on what bed of the Lexington in the 

 Ohio River exposures the Cynthiana rests. 



Conditions are similar along the Licking River, which roughly 

 parallels the Ohio to the southwestward. The still older 



* Science, Aug. 4, 1905. 



Am. Jour. Sci. — Fourth Series, Vol. XL, No. 240. — December, 1915. 

 44 



