374 
HUBBARD AND CRONEIS 
series, one of which has its greatest development in East Tenn- 
essee. In this (the Pearisburg area) locality, however, the 
Chickamauga embraces every important member of the forma- 
tion as developed in Tennessee. There is evidence of only a 
small unconformity between this formation and the Shenandoah, 
and yet, if we have correctly correlated these strata, a consid- 
erable time break exists. This is no doubt represented in part 
by the breccia described above. 
Following the Chickamauga is the Moccasin limestone, which 
is calcareous near its base, but which becomes very arenaceous 
near the top. This formation is clearly a gradational one repre- 
senting the time between the deep seas in which the Chicka- 
mauga was deposited and the shallow seas wherein the Bays 
was laid down. It is due no doubt to the gentle uplift which 
began in the time just preceding the early Trenton. In the east- 
ern trough we have, as the equivalent of the Moccasin, the Tellico 
sandstone. After this time, the Sevier formation was deposited 
quite uniformly in both troughs. The Sevier in its various divi- 
sions is equal to the upper Utica, and the Eden, and as would be 
supposed, grades from calcareous at the base to arenaceous at 
the top. The Sevier (as well as the Moccasin) may be regarded 
as an intermediate formation fore-running the Bays. 
At about the end of the Trenton, the troughs were elevated 
quite rapidly and as a consequence, communication with the 
Atlantic was cut off at the south where the elevation was the 
greatest. At the same time, the middle portions of the Lenoir 
Trough sank and permitted the waters from the Mississipian 
sea to invade. The result of this revolution is the Bays and 
Clinch sandstones as well as the lower and non-ferruginous shale 
members of the Rockwood. The southern end of the trough con- 
tinued to be uplifted as is shown by the fact that of the three 
mentioned formations, the Bays extends farthest to the south, 
the next, not quite so far and the third, the Rockwood, falls still 
short of the Clinch. In spite of the fact that there is an uncon- 
formity between the Rockwood and the Giles, (indicating uplift 
and erosion in Giles County) when Devonian sediments were laid 
down, the seas were again deeper in this area than off to the 
south. This is clearly shown by the fact that these sediments are 
but 25 feet thick at Chattanooga yet are nearly 5000 feet in thick- 
ness on the New River. 
