190 The Lower Devonian Deposits of Maryland 



Vertical Total 

 thickness vertical 

 feet thickness 

 gigantca (a), Rensselwria marylandica (c), Beacfiia ovalis 

 (rr), Stropheodonta magnifica (rr), Leptrrna rhomboidalis var. 

 ventricosa (r), Chonostrophia complanata (rr), Dalmanella 

 planiconvexa. Lingulapholis terminalis (rr), Avicula textilis 

 arenaria (rr), A. gebhardi (rr), Diaphorostoma ventricosum 



(rr) , Platyceras nodosum (r) , P. cf. gebhardi (a) 12.0 63.0 



Covered 10.0 51.0 



Light gray massive arenaceous limestone 8.0 41.0 



Covered 2.0 33.0 



Heavy dark gray limestone with conglomeratic bands at top. 

 Bands four or five inches thick consisting of small quartz pebbles 



and coarse sand. Diaphorostoma ventricosum, (rr) 10.0 31.0 



Covered 6.0 21.0 



Conglomeratic dark gray limestones. Fine pebbles and coarse 

 sand throughout this limestone 3.0 15.0 



Total thickness of Oriskany formation 52.5 



Heldebberg Foemation 



Becraft Member 



Light gray massive limestone. Spirifer concinnus (aa), S. 

 cyclopterus ? (r), Meristella arcuata (c), Schuchertella wool- 

 worthana (rr) 12.0 12.0 



The Oriskany consists of about 52 feet of limestone with scattered beds 

 of coarse sand and also some layers of black chert. This is in very strong 

 contrast with the Oriskany exposed at Hancock, only a short distance 

 farther west, where it is almost pure silica throughout. The conglomerate 

 at the base of the Eomney is much heavier than that in the same position 

 on the south side of the creek. 



I 



