168 



INDEX TO THE STRATIGEAPHY OF NOETH AMERICA. 



The Ordovician strata of the central basin of Tennessee have been minutely 

 mapped and described by Hayes and Ulrich/^^"' who give the following classification, 

 and correlation with Safford's nomenclature : 



Generalized time scale 

 for central North 

 America. 



Richmond. 



Lorraine. 



Frankfort. 



Utica. 



Trenton. 



Black River. 



Stones River. 



Mappable lithologic 

 equivalents in the 

 Columbia quadrangle. 



Fernvale formation. 



(Wanting.) 



Leipers formation. 



Safford and Killebrew, Ele- 

 ments of the geology of Ten- 

 nessee, 1900. Middle Ten- 

 nessee. 



(Wanting.) 



Catheys limestone. 



Bigby limestone. 



Hermitage formation. 



(Wanting.) 



Carters limestone. 



Lebanon limestone. 



(Not exposed.) 



Hudson (College Hill; Cincin- 

 nati). Includes Hudson phos- 

 phate. 



Safford, Geology of Tennessee, 

 1869. Middle Tennessee. 



Upper Nashville. 



(/)(?) Cyrtodonta 



and Stromatopora 



beds, 

 (d) (c) Dove and 



Ward limestones, 

 (c) Capital limestone 



or Mount Pleasant 



phosphate. 



(6) Orthisbed. 



(Not classified.) 



(a) Carters limestone. 



Lebanon limestone. 



Ridley limestone. 



Pierce limestone. 



Murfreesboro lime- 

 stone. 



Nash- 

 ville 



(Tren- 

 ton). 



Stones 

 River . 

 (Chazy). 



Middle Nashville. 



Lower Nashville 

 (Orthis bed). 



' Nashville. 



Carters Creek lime- 

 stone. 



Glade limestone. 



Ridley limestone. 



Pierce limestone. 



Central limestone. 



Trenton or 

 Lebanon. 



J 11-12. GREAT BASIN, NEVADA AND ITTAH. 



A zone containing Trenton fossils is distinguished at Eureka, Nev., in the base 

 of the Lone Mountain limestone, which is unconformable to the Eureka quartzite 

 below. The limestone is 1,800 feet thick and is all of Ordovician age. Fossils found 

 in the upper part were assigned to the "Upper Silurian" by Hague,'®^ but they are 

 now regarded by Ulrich" as of Richmond age (uppermost Ordovician). The dis- 

 tribution of the Lone Mountain limestone is not well known. The limestone or its 



(J Personal note. 



