404 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



As a result of the writer's study of the geology of the region, however, the conclusion has 

 been reached that only the Floyd shale and the rocks included by the Alabama Survey in the 

 "Bangor or limestone phase" are contemporaneous. The Parkwood formation of Shades 

 Valley and Blount Mountain is absent from the section in Murphrees and Brown valleys, hav- 

 ing been eroded west of Birmingham VaUey before the deposition of the Pottsville or "Coal 

 Measures," so that they rest unconformably on the Pennington shale. 



The variations in the stratigraphy of the Mississippian formations above the Fort Payne 

 chert are shown in the sections below: 



Section of Mississippian rocks above the Fort Payne chert in Brown and Murphrees valleys. 



Pottsville formation. reet. 



Pennington shale 100 



Bangor limestone: 



Limestone 350 



Shale 30 



Sandstone (Hartselle member) 100 



Shale 50 



limestone 160 



Fort Payne chert. 



•^ 790 



Section of Mississippian rocTcs above the Fort Payne chert near Irondale. 



Pottsville formation. Feet. 



Parkwood formation, shale and sandstone 2,000 



Pennington shale, dark, calcareous (?) 292 



Bangor limestone: 



Limestone 317 



Shale, soft, dark, calcareous (?) 39 



Sandstone (Hartselle member) 117 



Shale, dark, calcareous (?) 97 



Limestone 88 



Fort Payne chert. 



2,950 



Still farther south, in the vicinity of Readers Gap, borings show only dark shale, probably 

 calcareous, in the 500 feet immediately over the Fort Pajme chert. The well logs are cor- 

 roborated in the main by aU that can be seen of the formation. South of Boyles Gap and 

 Oxmoor good sections and accurate measurements of the rocks under discussion are not obtain- 

 able. A compiled section for the region south of Oxmoor, probably a close approximation, 

 is as follows: 



Pottsville formation. Feet. 



Parkwood formation, shale and sandstone 2,000 



Floyd ehale: 



Shale, some calcareous, sandstone, and limestone lenses 700 



Sandstone (Hartselle member) 100 



Shale, dark, calcareous 200 



Fort Payne chert. 



•' 3,000 



