PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 57 
Columbiana formation (B. N. Cooper and G. A. Cooper).—In southeastern 
belts of the Appalachian Valley in Alabama, the Pratt Ferry limestone is suc- 
ceeded by a body of black graptolitic shale varying in thickness from a few 
inches up to 325 feet. The variation in thickness of the shale reflects the major 
disconformity between it and the overlying Devonian Frog Mountain sandstone. 
The Columbiana shale is approximately the same as the Rich Valley shale of Vir- 
ginia and the Paperville shale of the Bristol district of Virginia and Tennessee. 
The profusion of graptolites in the Columbiana shale has been described by 
Decker (1952, pp. 14-26) from exposures near Pratt Ferry, Blocton (15’) 
Quadrangle, Ala. The type section of the Columbiana formation is just west of 
Simpson Spring, 24 miles northwest of Calera. The name is from the Colum- 
biana (15’) Quadrangle in which the east side of Calera is located. 
Brachiopods are rare in the black shales, and only one is listed from the 
Columbiana formation : 
Lingulella tenuitesta Cooper. 
Curtin formation.—This formation (Kay, 1944, p. 19) is exposed in parts 
of Centre, Clinton, and Lycoming Counties, Pa., and ranges in thickness from 
o to 150 feet. The formation is composed of two members: Valley View and 
Valentine. (See further discussion under these headings. ) 
Dot formation.—This name was proposed by Miller and Brosge (1950) for 
dolomitic limestone, reddish and green mudstone, dove-gray limestone, and light- 
gray dolomites with a prominent conglomeratic zone of chert and dolomite peb- 
bles at the base. The name is from exposures along Virginia State Highway 
70 just west of Dot, but the type section is from the blind spur at the south end 
of the railroad cut at Hagan, Rose Hill (T.V.A. 161-NE) Quadrangle. No 
fossils were seen or have been reported. 
Correlation of Dot formation—Only lithology and position can be used to 
correlate this formation. Lithology indicates a correlation with the Blackford 
facies at the base of the Middle Ordovician sequence in western Virginia, but 
its position indicates that the Dot formation is probably a correlative of the 
Lincolnshire-Elway formations. 
Douglas Lake member of Lenoir formation.—This name was proposed 
by Josiah Bridge for exposures at Douglas Lake Dam. The rocks are an argil- 
laceous dolomite attaining a maximum thickness of 30 feet and usually conglom- 
eratic at the base. The type section is 14 miles upstream from Douglas Dam, 
near Shady Grove on the Kykers Ferry (T.V.A. 156-NE) Quadrangle. The 
Douglas Lake dolomites underlie Lenoir limestone with Rostricellula, The mem- 
ber is patchy in occurrence. The facies is like that of the Blackford which dis- 
places the Lenoir to the west. 
Doylesburg member of Shippensburg formation.—This member overlies 
the Fannettsburg member of the Shippensburg formation and is unconformably 
overlain by the Nealmont formation. The member was named by Craig (1940, 
Pp. 727) with its type section 1 mile S. 70° W. of St. Thomas, Pa. The forma- 
tion consists of dove, massive, white-weathering limestone in the eastern belts, 
