Maryland Geological Survey 107 



TentacuUtes gyracantJius and Meristella sp. abundant in the upper part of 

 the section. 

 Coral zone (Keyser coral zone ?). 

 Cystid zone — Sphwrocystites sp. 

 Stenochisma formosa zone. 

 Rhynchospira globosa zone. 



The Gypidiila cccymancnsis var. prognosiica zone was not observed. It 

 is believed that a more thorough examination would establish still more 

 closely the essential siriiilarity of the faunas of both areas. 



The underlying Tonoloway consists of hard, platy, dark blue limestone 

 breaking with a clean,, flat cleavage and contrasting strildngly with the 

 nodular basal beds of the Keyser. A more massive bed 4 feet thick is 

 present at the top of the Tonoloway. The transition from the Keyser to 

 the Tonoloway is abrupt. The fauna of the latter fonnation consists 

 chiefly of ostracods. All these features ai-e characteristic of the same 

 strata in Maryland. 



The underlying (Waterlime) of Claypole appears essentially the same 

 as the Wills Creek fonnation of Maryland. These facts permit little doubt 

 that the Clarks Mill shale embraces the Keyser and Tonoloway of Mary- 

 land. The Coeymans is not exposed and is perhaps absent. 



An excellent section of the Helderberg is seen in the cuts of the North- 

 ern Central Railroad on the Susquehanna River at Selinsgrove Junction, 

 about 40 miles northeast of the preceding locality. The Helderberg is 

 exposed in two anticlines at this place both of which are described by 

 White.' 



The section is exposed in the anticline north of Selinsgrove Junction. 

 It begins at a cave-like excavation north of the 135th mile post of the 

 Northern Central Eailroad and extends southward to the end of the 

 exposure.^ 



' Rept. 2d Geol. Survey Pa., vol. G7, 1883, pp. 343-348. 



= The writer is greatly indebted to Mr. H. K. Schock, formerly of Susque- 

 hanna University, Selinsgrove, Pennsylvania, who measured this section and 

 collected fossils from it. 



