684 J. W. T3EEDE BEDS OF APPALACHIAN AND WESTERN SECTIONS 



the second is the correlation of the Appalachian and the Kansas-Texas 

 sections; the third is the evidence of climatic change during the time 

 concerned, and possible migrations of vertebrates and plants. 



Age of the Appalachian and the avestern Red Beds 



If the facts thus far presented warrant the correlations made between 

 the Appalachians and the western interior regions, it will be a simple 

 matter to determine the relative age of the red beds of the two regions. 



In the Appalachian region the oldest Pennsylvanian red beds are found 

 a short distance below the Ames limestone, in the Conemaugh formation 

 of West Virginia, Ohio, and Pennsylvania, and are known as the "Pitts- 

 burgh red shales" in the West Virginia Survey Reports. Lately this 

 name has been replaced by the term Round Knob formation, since the 

 term Pittsburgh was preoccupied for another formation, the Pitts burgh 

 coal. It is in this formation that the vertebrates were discovered by Ray- 

 mond and I. C. White. Regarding its thickness and vertical extent in 

 Ohio Condit writes : 



"The beds vary from structureless, purplish red clay to deep red. even-bedded 

 shale, which may alternate with bluish layers. The more sandy portions fre- 

 quently show ripple-marks and sun cracks." 



"In the southern part of the State, where the Ames limestone is generally 

 thin or wanting, the Round Knob red beds are continuous, with similar strata 

 above the Ames horizon for many feet, and locally even reach nearly to the 

 Pittsburgh horizon'' [top of the Conemaugh]. 22 



From this it is plain that nearly the whole upper Conemaugh locally 

 may be largely composed of red beds. The base of these beds is slightly 

 below T the middle of the formation, below 7 which there are no true Penn- 

 sylvanian red beds. 



In the various county reports of the West Virginia Geological Survey 

 the detailed sections of the Conemaugh are given. 



In some sections of the Dunkard in Pennsylvania the red beds seem 

 locally to be nearly missing, while there are several beds present in other 

 localities. 23 



These red beds are unknown below 7 the Round Knob or "Pittsburgh 

 Reds" horizon of the Conemaugh. In the region south of the outcrop of 

 the present Conemaugh formation nearly or quite all of the upper Cone- 

 maugh and perhaps much of its lower part would probably have been red 

 had not these rocks been removed by erosion; so that it is impossible to 



- Condit : Ohio Geol. Survey, Bull. 17, p. 36, 1912. 

 23 Data from West Virginia Geological Survey reports. 



