740 C. 0. Dunbar — Stratigraphy and Correlation 



entirely different. Faunally, however, it seems to agree 

 with the latter, especially in the absence of the Camaro- 

 crini. It therefore seems highly probable that the 

 Pyburn limestone is the equivalent of more or less of the 

 Bear Branch ; and that the latter is a local shallow-water 

 phase is shown by its cross-bedding and the development 

 of oolite. The author therefore holds that if the Bear 

 Branch member could be traced southward it would be 

 seen to grade into the impure gray limestone of the 

 Pyburn. In this section the Pyburn member is uncon- 

 formably succeeded by Mississippian shales, but in the 

 next section to the south, on Dry Creek, the top of the 

 Pyburn member becomes more sandy and somewhat 

 irregularly bedded, and here it is separated by a slight 

 erosional unconformity from a massive, coarsely crys- 

 talline, white limestone which seems to represent the 

 Flat Gap member. 



The Ross member only is exposed along Horse Creek 

 on the Ross farm 5 miles southeast of Savannah and 

 again for 2 or 3 miles above Rockhouse. This same mem- 

 ber is exposed in the bluffs along the Tennessee River 

 below Cerro Gordo, more extensively at Grandview, and 

 also outcrops along tributaries of Indian Creek 3 or 4 

 miles east of Cerro Gordo. 



At Olive Hill, where the three members are present, the 

 total thickness is over 150 feet; the Ross and a part of 

 the Bear Branch members are present near Clifton, but 

 only a part of the Ross at Grandview; in the vicinity of 

 Saltillo the whole formation is missing, the younger and 

 southwardly overlapping Birdsong formation with its 

 Eospirifer macropleura fauna here resting directly on 

 the Decatur limestone. The progressive thinning of the 

 Olive Hill formation toward the north and west, by the 

 disappearance of the higher members first, strongly indi- 

 cates a considerable interval of erosion following the 

 deposition of this formation and preceding the Birdsong 

 shale. So thick a series of limestones, with the upper 50 

 feet, especially, pure and heavy-bedded, must in all prob- 

 ability have extended farther north than the 12 or 15 

 miles which separates Olive Hill from Grandview and 

 Saltillo. 



The fauna of the Olive Hill formation is chieflv devel- 

 oped in the Ross membpr, from which fifteen species pass 

 upward into the Bear Branch and four continue into the 



