PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER Fy. 
Along the northwest base of Clinch Mountain west of Gate City the Lincolnshire 
formation is underlain by a section with conglomerate at the base, succeeded by 
light-gray to pink massive calcarenite containing worn colonies of Billingsaria. 
Minor portions of shale, mudstone, and calcilutite may be present. Dinorthis 
holdeni (Willard) occurs in the upper part. The formation ranges from 120 to 
300 feet thick. The basal beds contain Rostricellula basalaris Cooper. The 
formation is thus a calcarenite equivalent of the Elway and Tumbez. The forma- 
tion name is from Marcem Quarry, 2 miles west of Gate City, Va. 
Martin Creek formation.—Miller and Brosge (1950) proposed this name 
for dark-gray and brown limestone smelling of oil, with chert nodules and tan 
cryptocrystalline limestone with abundant chert nodules in the upper part. The 
thickness is 40 to 180 feet. It is named for exposures at the mouth of Martin 
Creek, Back Valley (T.V.A. 161-SE) Quadrangle, Virginia-Tennessee. The 
following brachiopods were identified : 
Camerella sp. Rhipidomena tenuitesta (Willard) 
Multicostella cf. M. saffordi (Hall and Clarke) Schizambon sp. 
The formation is uncertainly correlated with part of the Ward Cove formation. 
Martinsburg formation.—This formation consists of a thick mass of silty 
and arenaceous shale overlying the great body of Middle Ordovician limestones 
in the Appalachian Valley. The base of the formation, as exhibited near Green 
Mount Church, about 5 miles north of Harrisonburg, Va., contains some thin 
beds of limestone and has the fauna of the Salona formation of Pennsylvania. 
The higher Martinsburg formation contains Eden and Maysville fossils, but only 
the basal portion is of concern in this monograph. In southwestern Virginia and 
East Tennessee the base of the Martinsburg formation contains thin-bedded 
limestones abounding in Dinorthis and a large Sowerbyella. This part of the 
section is correlated with the Curdsville formation of Kentucky. Brachiopods 
are abundant at the base of the formation in most areas. 
Brachiopods taken from the lower Martinsburg (Salona) near Green Mount 
Church, Broadway (15’) Quadrangle, Va.: 
Colaptomena leptostrophoidea Cooper Parastrophina sp. 1 
Cyclospira quadrata Cooper Paucicrura subplana Cooper 
Cyphomena grandis Cooper Petrocrania trentonensis (Hall) 
Dalmanella sculpta Cooper Phragmorthis crassa Cooper 
Eoplectodonta alternata (Butts) Plectorthis ponderosa Cooper 
Laticrura magna Cooper Skenidioides elongatus Cooper 
Leptaena ordovicica Cooper Sowerbyella cava Cooper 
Orthambonites bielsteint Cooper S. eximia Cooper 
Oxoplecia globularis Cooper Strophomena bellilineata Cooper 
Parastrophina hemiplicata (Hall) 
Brachiopods from the lower Martinsburg (Curdsville) in southwestern Vir- 
ginia and Tennessee: 
Dalmanella rara Cooper 
Dinorthis pectinella (Emmons) 
Hesperorthis tricenaria (Conrad) 
