TITLES AND ABSTRACTS OF PAPERS 137 



MIDDLE 0RD0VIL'JA\ OF VIRGIMA A\D TESNESSEE 

 BY PERCY E. RAYMOND 



(Abstnirt) 



Strara of MiddU- Ordoviciaii aije outeTOi) on the wostorn sides of a series 

 of parallel fault-blocks in Virixinia and Tennessee, and in passinj; from block 

 to blo<*k a different develoi)nient is found iu each. Very considerable differ- 

 ences in lithology and fauna in the various blocks have led to an interpretation 

 in which each bloik is thought to have been a separate trough, with its own 

 I»e<*uliar life and seiliments. 



Re<^ent investigations in the field, made with the aid of the Shaler Memorial 

 Fund, liave led the writer to the belief that there is much physical and faunal 

 evidence in favor of the older view, that the observed differences are due to 

 distance from the shore, depth of water, and other local conditions. Sections 

 and fossils which illustrate a transition from one "trough" to another will be 

 descrilMMi and a sunnnary of the prol)able sequence of events presented, show- 

 ing the possibility of continuous deposition in the area from early Chazy 

 to late Trenton time, with a single emergence of short duration during and 

 after the Lowville. 



Presented by title by request of the author. 



NOTES OS THE ORISKWY AXD HELDERBERO IN VIRGINIA 

 BY R. J. HOLDEN 



(Abstract) 



Southwest of the New Itiver those formations which may include the Oris- 

 kany and Helderberg have relatively meager development. The members of 

 the Oriskany and Helderberg and their distribution are unknown. 



Northeast of the New Kiver these formations have a greater development, 

 particularly the Helderberg. The Oriskany is represented by the Monterey 

 sandstone. This is a definite lithologic unit — a calcareous sandstone. It is 

 sharply limited above by a knife-edge contact with the Romney shale and less 

 8haiT)ly limited below by the Lewistown limestone. The Helderberg is in- 

 eluded in the upper part of the Lewistown limestone. The Lewistown is a 

 thick formation and divisil)lc into several units. The upi)er member is named 

 the I»ngdale limestone. This latter has two lithologic phases — a Hint-free 

 limestone above, with a thickness of 30 to 50 feet, and a flinty limestone below, 

 witli a thickness of 20 to 30 feet. Below the Longdale there is a* member 

 nanieil the Traigsvllle limestone. This is a pure limestone and has a thick- 

 ness of alx)ut ir>0 feet. 



Tlie Longdale limestone Is c<)iirl:ircd witli the Hecraft. and the Craigsviiie 

 limestone is correlate<l with the New Scotland. 



Presented by title by request of the author. 



