THE SHARON ENCROACHMENT 273 



gion. Subsequent study of the Sharon coal flora has shown this to be 

 clearly erroneous. The horizon of this flora is much higher th an Raleigh 

 and probably as high as the Nuttall sandstone, though it may fall a little 

 lower. Although further study of the plants of the various series may 

 necessitate subsequent revision of my conclusions, the paleobotanical 

 evidence available at present appears to point toward the Nuttall horizon, 

 thus agreeing with the correlation reached by Doctor Stevenson* quite 

 independently and wholly on stratigraphical grounds. The study of 

 the fossil plants from the series of southwestern Virginia and eastern 

 Kentucky is not yet completed, f but it is plain that the horizon of the 

 Sharon coal is fully as high as the top of the Wartburg sandstone of 

 Keith in the Briceville and Wartburg quadrangles of north Tennessee, 

 or the Glade sandstone of Campbell in the Bristol and Estillville quad- 

 rangles of southwestern Virginia and Kentucky. The Corbin sandstone 

 on the western border of the Kentucky region would seem, so far as the 

 plants have been studied, to fall near the Glade and Wartburg, and I am 

 provisionally disposed to agree with Doctor Stevenson $ in placing 

 Corbin in the Sharon horizon. It certainly is not younger than Sharon. 

 If differing in age, it is older. I 



In the Southern Anthracite field the place of the Sharon conglomerate 

 is about 400 feet below the Buck Mountain coal. It is doubtful if the 

 Sharon was deposited in the Northern Anthracite field or in the north- 

 eastern bituminous basins. 



SHARON OVERLAP 



That portion of the area of Sharon conglomerate which lies beyond 

 the limits of the Raleigh deposition in the Appalachian coal fields is 

 shown on the map by the shade next lighter than that of the Raleigh. 

 Much uncertainty as to the position or even the presence of the Sharon 

 conglomerate in the regions of the Monongahela and Dunkard forma- 

 tions arises from the difficulty of interpreting the drill records in this 

 area in West Virginia, Pennsylvania, and Ohio. The occurrence of the 

 conglomerate is irregular in northern Ohio, and the Connoquenessing 

 sandstone is reported II by Dr I. C. White as resting on the Mississippian 

 in Lawrence county, in western Pennsylvania. It is believed, however, 

 that the mapping is in the main approximately correct. It will be 

 noted that the Sharon area or overlap extends to the northwest far be- 



*See this volume, p. 206. 



t Twentieth Ann. Rept. U. S. Geol. Survey, 1900, pt. 2, p. 819. See age of Breathitt formation. 

 J See this volume, p. 206. 



\ On some accounts it appears possible that the Corbin sandstone may correspond to one of the 

 lentils of the Sewell formation on New river. 



|| Second Geol. Survey of Pennsylvania, Rept. of Progress QQ, pp. 68, 69. 



