40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 127 
sionally wonderfully fossiliferous, as in the vicinity of Friendsville, Tenn. (5) A 
dolomitic facies is the final prominent carbonate rock facies. This type of rock 
sonsisting of light-gray dolomite or dolomitic limestone is prominent at the base 
of the Middle Ordovician in many belts. It is well displayed in the Blackford, 
Surgener, Pamelia, Long Savannah, and other formations. These rocks, although 
at the base of the sequence, are quite clearly of different age across the geosyn- 
cline. This is probably true also of the Pamelia formation of New York. The 
statement can be truly demonstrated in the Appalachians where the Blackford 
formation is equivalent to the Lenoir, but the Surgener formation, which is like 
the Blackford lithologically, contains marine fingers with fossils of the Lincoln- 
shire (Hogskin member). 
The facies diagrams.—Figures 2 and 3 represent ideal diagrams of the facies 
relationships roughly north and northeastward from the belt along the base of 
the Great Smoky Mountains to the exposures at High Bridge, Ky. The sequence 
would be essentially the same if it had been taken from the same beginning point 
to the Central Basin of Tennessee. The diagrams show a great wedge ranging 
in thickness from 7,000 to 9,000 feet on the east to about 600 feet on the west 
side. The eastern and thickest part of the wedge consists of clastics, coarse only 
in the extreme eastern and upper part of the column. The main mass of the 
clastics is sandy shale and sandstone, in some places limy and in others quite 
shaly. In the central portion of the diagrams the sequence has become shaly 
and limy with sand definitely subordinate except for the marbles which are 
actually a kind of coarse sand possibly formed by a continuously growing com- 
munity of crinoids and cystids. The western and tapering edge of the wedge is 
composed of moderately thick and thin-bedded limestone, the so called “dove” 
limestone or Lowville facies. This facies evidently covered a great shelf area that 
occupied much of Tennessee and Kentucky in Ordovician days. It must be 
borne in mind that these diagrams are idealized and conventionalized and are 
not drawn to scale. It would be difficult to portray the facies intelligibly if the 
diagrams were to scale. 
Comparison with Devonian facies of New.York.—Perhaps the best exhibition 
of Paleozoic facies across a geosyncline is that exhibited by the great wedge 
of Middle Devonian sediments that extends from the Catskill Mountains to 
Lake Erie near Buffalo. The form of the Devonian wedge is like that of the one 
in Tennessee, but some differences are obvious. In the Devonian the red-bed 
facies occupies nearly the entire sequence in extreme eastern New York, and 
coarse conglomerates are present in the upper part of the sequence. In other 
words the Devonian facies are more developed as regards the clastics than the 
Tennessee wedge. It is suggested that this coarse clastic portion of the Ordovi- 
cian facies is either overridden by the Great Smokies or was obliterated by 
mountain-making and accompanying contemporaneous igneous intrusions. 
In the Devonian wedge a great development of black shales fingers with the 
sandy clastics to the east but occupies much of the section on the thinned edge 
of the wedge. This condition may be due to unusual paleogeographic conditions 
in the Devonian, such as a lowland to the north and west, that might have fur- 
