154 The Lower Devonian Deposits of IMaryland 



Section A 

 Helderbeeg Formatiox 



Horizontal 



Eeyser Memier disu,„ce ^^^^ ^^.^^^^^^ 



West wall of quarry 111.8 



Gypidula zone. Heavy-bedded, gray-blue limestone, 

 Gypidula coeymanensis var. prognostica throughout. 

 At the top were found, in thin-bedded shaly limestone, 

 Batostomella interporosa, Fenestella (Cycloporina) 

 aUidorsata, FistuliporeUa cumulata. Orthopora rhom- 

 bifera, Thamniscus regularis, Leptwna rhomb oidalis 

 (r), Oypidula coeymanensis var. prognostica (aa), 

 crinoids (a). At the bottom occur Dalmanella sp., 

 Stenochisma sp 111.8 8.0 111.8 



Gray-blue arenaceous limestone. Crinoids (aa).... 103.8 1.4 103.8 



Gray-blue limestone, heavy-bedded with some thin 

 beds. The lower 5 feet have a greenish cast „. . 102.4 10.0 102.4 



Solid massive dark blue limestone. A Stromatopora 

 bed occurs at the bottom of this unit. Few fossils seen 92.4 



East wall of quarry 70.0 



Thin-bedded argillaceous limestone with interbedded 

 bands of arenaceous limestone. Concealed in part. . . . 70.0 



Heavy-bedded dark blue limestone. Concealed in part 20.0 



Concealed. 



Total thickness of Keyser member described 111.8 



Section B 



Hyndman Section B is exposed on the south side of the road about 1150 

 feet southwest of Hyndman Section A. There are two quarries here. 

 The quarry farthest west and nearest the road has been called the Upper 

 quarry zone by Professor Schuchert. It is in a Stromatopora bed of the 

 upper part of the Keyser and at present is abandoned. It contains Stroma- 

 topora constellaia. Going east of the Upper quarry there is a concealed 

 unit east of which is situated the Lower quarry, at which work is being 

 done at present. It is in the purer limestones lying between the Gypidula 

 zone and a Stromatopora bed, the Gypidula zone being the hanging wall 

 and the Stromatopora bed the foot wall of the quarry. This quarry is in 

 the same beds as those worked in Section A. 



The section begins at the top of the Gypidula coeymanensis var. prog- 

 nostica zone on the west wall of the quarry. 



22.4 



92.4 





70.0 



50.0 



70.0 



20.0 



20.0 



