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NEW YORK STATE MUSEUM 



This therefore must be considered not far from the southern 

 boundary of the Helderberg sea. 



What appears to be another case of overlap of the upper 

 beds to the east, is found near Big Stone Gap and other portions 

 of southwestern Virginia. Here a coarse sandstone is suc- 

 ceeded by 70 feet of limestone, silicious at the base but porous 

 upward, when a bed with Leperditia occurs. This is probably 

 the Manlius. Above this are coarse grained calcareous sand- 

 stones made up largely of O r t h i s oblata, C a m a r o - 

 toechia ventricosa and Meristella. This appears to be 

 late New Scotland, which here rests by overlap on the Manlius. 

 Above the sandstones are cherty limestones (the Hancock lime- 

 stone of the Estillville and Bristol folios) with crinoid stems, 

 A s p i d o c r i n u s s c u t e 1 1 i f o r m i s , Chaetetes, Favosites, 

 A t r y p a reticularis, Leptaena r h o m b o i d a 1 i s , 

 Stropheodonta, Spirifer c y c 1 o p t e r u s , Meristella, 

 Camarotoechia nucleolata, Orthis oblata and 

 others. This also represents late New Scotland or early Becraft 

 time. The thickness of these two beds is not much over 150 feet. 

 Above them lie 35-40 feet of coarse reddish sandstone of Oriskany 

 age, containing H i p p a r i o n y x p r o x i m u s , Meris- 

 tella lata, etc. 1 



Near Perryville Tenn. the Linden limestone rests on the Menis- 

 cus limestone or Brownsport bed. 2 The Linden contains a fauna 

 suggestive of New Scotland or later age and is succeeded by the 

 Camden chert of Oriskany age. The base of the Linden shows 

 no marked unconformity so far as known, but appears to be a 

 crinoidal lime sandrock. The Brownsport may be the equiva- 

 lent of the Decker Ferry and other beds of Salina age, and in 

 part may also represent the Manlius. 



In southeastern Illinois and in Missouri the upper part of the 

 Clear Creek limestone contains an upper Helderbergian fauna, 



1 Stevenson. Am. Phil. Soc. Proc. 1880-S1. 19:98, 234. 

 2 Foerste, A. F. Jour. Geol. 11:581, G80. 



