86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
S. subconica Cooper T. minor Cooper 
S. willardi Cooper Trematis elliptopora Cooper 
Skenidioides convexus Cooper T. ? spinosa Cooper 
Spinilingula intralamellata Cooper Triplesia carinata Cooper 
Spondylotreta concentrica Cooper Tropidothyris pentagona Cooper 
Taphrorthis peculiaris Cooper Undiferina rugosa Cooper 
Titanambonites amplus (Raymond) Westonia superba Cooper 
Torynelasma toryniferum Cooper Xenambonites undosus Cooper 
Correlation of Pratt Ferry formation.—The fauna of the Pratt Ferry forma- 
tion is obviously closely related to that of the Arline formation and its correla- 
tives. The position of the formation is most interesting because it really is a 
part of the Little Oak formation. Cambrian elements, such as Lingulella, and 
Dictyonites which is a member of the family Micromitridae, form another inter- 
esting feature of the fauna. 
Red Knobs formation (B. N. Cooper and G. A. Cooper).—The Red Knobs 
formation is a thick succession of red to pink calcarenites and limy ferruginous 
sandstones up to 750 feet in thickness. The exposures from which the name 
is taken are near and along the Blount-Loudon County line, near Meadow, on 
the Meadow (T.V.A. 139-NW) Quadrangle. The lower part of the Red Knobs 
formation consists of red to pink marble—the Holston marble of Ulrich, Gordon, 
Rodgers, and others, which is well exposed in the old marble quarries just south- 
east of Friendsville, Louisville (T.V.A. 138-SE) Quadrangle. The upper beds, 
which yield a characteristically dark-maroon, sandy regolith, are calcareous sand- 
stones and ferruginous sandy calcarenites with partings of greenish-gray to buff 
shale. The marble beds contain Multicostella, Atelelasma, Oxoplecia holstonen- 
sis, and numerous bumastid trilobites. 
Dinorthis venusta Cooper O. holstonensis Willard 
Obolus ? grandis Cooper O. marmorata Cooper 
O. ? virginiensis (Willard) Philhedra ferruginea Cooper 
Oligorhynchia inex pectata Cooper Skenidioides costatus Cooper 
Oxoplecia gibbosa Cooper Valcourea sp. 3 
Correlation of Red Knobs formation.—By position and faunal character this 
formation is correlated with the Benbolt. It occurs above the Arline. Its assem- 
blage of species seems to be from the Arline. 
Rich Valley formation (B. N. Cooper and G. A. Cooper).—This forma- 
tion consists of black and chocolate-brown shales, containing abundant grapto- 
lites, brachiopods, and trilobites, which range in thickness from a few feet to 
350 feet. The type section is immediately south of the Porterfield Quarry and 
Worthy Mine of the Mathieson Chemical Corp., about 7 miles east-southeast of 
Saltville on the Maccrady (T.V.A. 218-NW) Quadrangle, Smyth County, Va. 
The basal 40 feet of black shaly limestone which capped the limestone reef in 
Porterfield quarry (G. A. Cooper, 1940, pp. 17-20) constitutes the lower part of 
the Rich Valley formation. These beds have yielded some of the most remark- 
able fossils found in the Appalachian Valley, and most of the species listed below 
are from this part of the Rich Valley. At Quarry Village, south of Saltville on 
the Glade Spring (T.V.A. 212-SE) Quadrangle, the base of the Rich Valley 
