STRATIGRAPHIC CLASSIFICATION— DIASTROPHIC CRITERIA 413 



of the valley and confined to the middle and western parts. During this 

 time, then, the valley as a whole was tilted to the west, while in the 

 Canadian the east side was depressed and the middle and western parts 

 relatively elevated. The Canadian is followed by the Stones Eiver lime- 

 stone. Of the three divisions of this series, the lowest is best developed 

 on the west side and thin or locally entirely absent in the middle and 

 eastern bands. A¥Tiere present in the latter it is represented by the Mos- 

 heim limestone. The middle division of the Stones Eiver again is thick- 

 est in the western strips, rather well developed bnt lithologically distinct 

 in the eastern part of the valley, where it constitutes the Lenoir lime- 

 stone, and entirely absent in the intermediate area. Except the Mosheim, 

 which is locally present, no rocks of Stones Eiver age are found in the 

 valleys flanking Copper Eidge. As to the upper division of the Stones 

 Eiver, this is found only in the western part of the valley. Presumably 

 it was deposited in this region only in the Clinton trough, the Pearis- 

 burg, Knoxville, and Athens troughs having been in a state of emergence 

 at this time. 



In the next or late Chazyan stage, represented in Tennessee by the 

 Blount group, the southern Appalachian sea was confined in northeast- 

 ern Tennessee at times to the eastern, at other times to the middle parts 

 of the valley. As a rule, sections in the Athens trough (on the east 

 side) and the Clinton and Newman troughs (on the west) contain no 

 beds of the early part of this stage, but occasionally in the latter, as at 

 Clinton, and in Mulberry Valley, northwest of Powell Mountain, Ten- 

 nessee, a subcrystalline limestone is found whose fauna, lithologic char- 

 acter, and stratigraphic position all clearly suggest the Holston. Fol- 

 lowing the Holston, we find the Tellico and Ottosee formations in the 

 medial area, the Tellico and Athens in the east, and the deposits of the 

 Black Eiver group, beginning with a strongly developed Lowville, mostly 

 on the west side of the valley. As elsewhere, considerable minor oscilla- 

 tions occurred also in this region during the Black Eiver, but the move- 

 ments were too complicated to be satisfactorily described in brief. 



During the remaining ages of the Ordovician the oscillations in the 

 Appalachian valley generally seem to have been relatively wider in scope 

 than before. In east Tennessee the submergences and emergences appear 

 to have affected the whole valley and at times extended westward to or be- 

 yond the Cincinnati axis. Deposition of red. Moccasin-like sediments 

 began in the west middle bands of the valley in early Black Eiver time, 

 but the typical Moccasin, which is late Black Eiver or early Trenton in 

 age, extended and possibly overlapped eastward and, according to pres- 

 ent evidence, passes into the calcareous Bays sandstone in the eastern 



