PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 4I 
nished the black shale. Nevertheless, black-shale development is less in the Ordo- 
vician wedge at the point the section was made. Had the section been taken 
through Bristol, Tennessee-Virginia, a greater development of the black shale 
would have been evident, but it is doubtful if it would have the enormous extent 
of that occurring in the Devonian. Furthermore, in the Devonian the black shale 
intervenes between the clastics and the limestones of the shelf facies. In the 
Ordovician wedge, on the other hand, cobbly limestones and limy shales with 
cobbles form an intermediate stage between the clastics and the limestones. The 
limestone facies is unlike that of the Devonian limestone in being composed of 
lime muds, whereas the corresponding facies in the Devonian contains more 
coarsely detrital limestone. Although the facies of the two periods are unlike in 
these minor respects, they are actually quite similar in their major aspects and 
show that a pattern existed in geosynclinal sedimentation. 
The author (or authors) of each new formation name appears after the name. 
Arline formation (B. N. Cooper and G. A. Cooper).—This name is taken 
for a limestone formation about 400 feet thick exposed almost in its entirety on 
both sides of the valley of a small stream tributary to Gallagher Creek, 2 miles 
southwest of the railroad switch at Arline on the Concord (T.V.A. 138-SW) 
and Louisville (T.V.A. 138-SE) Quadrangles, Tenn. The rock is mostly a 
cobbly-weathering, impure limestone containing considerable quantities of fine 
clastic material. It weathers by leaching of the lime to a yellow-brown soil con- 
taining numerous silicified fossils. The formation is underlain by dark, cherty 
limestone of the Lenoir formation and is overlain by shaly rock or calcarenite 
which is usually called “Holston marble” but is now the Red Knobs formation 
described herein as new. 
This limestone is of restricted distribution in eastern Tennessee. It extends 
northeast from its type section to Knoxville where it forms a fairly wide belt 
in the south environs of the city and in the neighborhood of Shooks Gap. To 
the southwest it interfingers with the silty calcareous beds of the Athens forma- 
tion. Fingers of the two types of sediment can be seen associated in the vicinity 
of Christiansburg, Sweetwater (T.V.A. 131-SW) Quadrangle, Tenn. South- 
west of the latter place in the vicinity of Athens and southwest of Calhoun the 
type Athens formation in its upper part is cobbly limestone like the Arline, con- 
taining numerous trilobites and a few brachiopods having affinities with those of 
the Arline formation. 
In the long and wide Ordovician belt along the west front of the Great Smoky 
Mountains fingers of this formation appear in the Tellico formation. These 
are especially well displayed along the Chapman Highway (Tennessee Highway 
71) near Cusick, Walden Creek (T.V.A. 156-SW) Quadrangle. The Ordovi- 
cian belt running from Philadelphia through Concord, just west of the Friends- 
ville belt, does not reveal this formation, but a shale underlying the Farragut 
marble south of Philadelphia contains one of the leading guide fossils of the 
Arline formation (Bimuria superba). On the west side of the syncline north 
of Morristown, at St. Clair, about 300 feet of Arline is exposed on the east 
side of the road in a small quarry and adjacent area. Here the formation fingers 
