136 The Lower Devonian Deposits of Maryland 



Vertical Total 

 thickness vertical 

 feet thickness 

 interporosa, FistuliporeUa cumulata, Atrypa reticularis, Rhyn- 

 chospira formosa, Schuchertella sp. 73.8, Vncinulus sp. 73, Cama- 

 rotoechia litchfleldensis 66 24.0 90.0 



Heavy-bedded, dark blue limestone. Very nodular toward 

 bottom. CamaroUrcliia litchfleldensis. Vncinulus convexorus, 

 Whitfieldella minuta 65, Atrypa reticularis. Camarotwchia 

 concinna, Murchisonia ? sp., Stenochisma formosa ? 58.4, Atrypa 

 reticularis, Chonetes jerseyensis, Rhipidomella sp., Rhyncho- 

 spira formosa, Spirifer eriensis 58, Camarotocchia litchfleldensis 

 50 and 47, Cyphotrypa. corrugata, Camarotcechia litchfleldensis, 

 Chonetes jerseyensis, Rhynchospira formosa, Schuchertella sp., 

 Vncinulus convexorus 39 27.0 66.0 



Very massive, hard, dark, nodular limestone. The top of this 

 unit forms the second large bedding plane above the base of the 

 Keyser. Atrypa reticularis, Chonetes jerseyensis, Stenochisma 

 formosa, Spirifer octocostatus, Stropheodonta bipartita, crinoid 

 rings. Camarotachia litchfleldensis, Whitfleldella minuta 2Z.. . 20.3 39.0 



Black, thin-bedded, very nodular limestone. Camarotcechia 

 litchfleldensis 18 3.1 18.7 



Nodular limestone with some chert Stropheodonta hipartita, 

 Whitfleldella minuta, ostracods 9.4. Stropheodonta hipartita, 

 ostracods 1 15.6 15.6 



Thickness of Keyser member 281.0 



ToNOLowAY Formation 



Fissile, calcareous shales 8.0 



Concealed. • 



The following species have been identified from the Keyser member at 



this locality, but their exact stratigraphic position is not known : 



Hindia sphseroidalis, Tentaculite zone. Nucleospira swartzi. Lower beds. 



Zaphrentis keyserensis. Camarotcechia lamellata. Lower beds. 



Cladopora rectilineata. Rhynchospira globosa. Lower beds. 



Aulopora schucherti. Rhipidomella emarginata, Lower beds. 



Ceratopora marylandica, Tentaculite Schuchertella marylandica. Lower 



zone. beds. 



Ceramopora micropora. Spirifer modestus var. plicatus. 



Atrypa biconvexa. Whitfieldella nucleolata. 

 Dalmanella concinna. 



II. Section at Dawson 

 At the southwest end of Fort Hill, about \ mile northeast of Dawson 

 Station on the Baltimore and Ohio Eailroad there is an excellent exposure 



