UTICA AND LORKAIXE SHALES 417 



Fossils are found mainl}^ in the soft ferruginous limestones and shaly 

 sandstones which are interstratified with the shales proper throughout 

 the w^hole horizon. The fossils though abundant are poorly preserved 

 as a whole ; the chief forms found are as follows : Calymmene callicephala, 

 CyrtoUtes ornatus Conrad, Lophospira acuminata Ulrich, Protowarthia plano- 

 dorsaia Ulrich, Trochonema nitidam Ulrich, Hormotoma gracilis (Hall), 

 Archinacella patelliformis (Hall), Modiolopsis modiolaris Conrad, Ctenodonta 

 pectimcaloides Hall, Orthodesma nasutum (Hall), Cleidophorus planidatus 

 (Conrad), Ctenodonta levata (Hall), Lyrodesma poststriatum (Emmons), 

 Byssonychia cincinnatiensis Miller, Orthorhynchida linneyi (James), Rajines- 

 qiiina squamida James, Dahnanella testudinaria midtisecta Meek, Zygospira 

 modesta Hall, Platystrophia lynx (Eichwald), Arthropora schnfferi Meek. 



The Utica and Lorraine shales, like the Mohawkian, contain faunas 

 very similar to those of New York. The lithological features of the 

 rocks are also strikingl}^ similar, indicating that the conditions of depo- 

 sition in the two regions were much alike. 



Summary 



This paper presents an account of a section of Ordovician rocks at 

 Bellefonte, Center count3^ Penns3'lvania. The rocks are well exposed 

 on each side of an unsymmetrical anticline, which forms Nittany valle}^ 

 between the isoclinal Bald Eagle ridge and the synclinal Nittany ridge. 



The Ordovician rocks exposed in this section are 6,752 feet thick ; 

 5,752 feet are limestones and 1,000 are shales. 



The rocks dip toward Bald Eagle at angles varying from 8 to 90 de- 

 grees, the dip increasing as the mountain is approached. The average 

 direction of the dip is north 30 degrees west. 



There are four fossiliferous horizons in the limestones and two in the 

 shales. Each of these horizons is separated from its successor by un- 

 fossiliferous beds, usually of great thickness. 



The lowest horizons, A-1 to A-3, inclusive, contain a Beekmantown 

 fauna. The total thickness of the Beekmantown rocks is 4,803 feet. 



Horizons A-4 to A-6, inclusive, contain a fauna w^hich may be re- 

 garded as of Stones River age. 



The remainder of the limestones are Mohawkian, both the Black 

 River formation and the Trenton being represented. The author has 

 found no evidence of the presence of either true Chazy or Birdseye 

 fossils. 



The Stones River group is 253 feet in thickness, the Black River is 93 

 feet, and the Trenton is 603 feet thick. 



Following the limestones is a series of shales, the lowest horizon in 

 the shales containing fossils of Utica age: the thickness of the Utica is 

 650 feet. 



