690 A. F. FOERSTE 



stone is often the only representative of the Black shale group. 

 The most southern localities at which phosphatic nodules were 

 observed were at W. D. Holton's home, 3^/^ miles northwest of 

 Waynesboro, and at the Taylor quarry near Iron City. 



The Hardin sandstone frequently attains a thickness of 7 to 8 

 feet. The greatest thickness observed was 11 feet. About a 

 mile northwest of Martin's mill, on Indian Creek, a fish plate, 4 

 inches long, was observed imbedded in this sandstone. At 

 several localities Barroisella siibspatidata was seen in the more 

 shaley layers immediately above the Hardin sandstone. These 

 layers form a transition to the Waverly, the Lauderdale cherty 

 beds of the Alabama Survey. The eastward extension of the 

 Hardin sandstone has not yet been determined. 



D. SILURIAN AND DEVONIAN STRATA OF THE WELLS CREEK BASIN. 



The Wells Creek Valley, southwest of Cumberland City on 

 the lower part of the Cumberland River in western Tennessee, 

 is 53 miles distant from Baker station, and 45 miles from Whites 

 Bend, Newsom, and Centreville. Both lithologically and faunally 

 the Silurian of the Wells Creek valley presents the facies of the 

 Silurian of the Tennessee River valley rather than the appearance 

 of the Silurian exposed on the western flank of the Cincinnati 

 anticline. 



About 3 miles southwest of Cumberland City, in a railroad cut 

 northwest of the home of John Broadus, there is a considerable 

 exposure of Ordovician rock, probably equivalent to the Saltillo 

 limestone, originally consisting of frequent alternations of clay 

 and clayey limestone, but now badly decayed and reduced in 

 large part to shaly material. Owing to a local, overturned fold, 

 the Silurian base is found south of the Ordovician exposure and 

 apparently dipping beneath it. The base of the Silurian section 

 consists of hard limestone, much faulted, estimated to be 22 feet 

 thick. The lower half is massive and contains Favosites favosiis. 

 The upper half contains cherty layers. Next in order of succes- 

 sion is a red, clayey rock, also faulted, estimated to be 14 feet 

 thick. At its base it is more whitish. At the top it grades into 

 limestone, 7 feet thick, less red and clayey above, containing 



