End_Page 1577------------------------------

Regional stratigraphic studies of the Middle and Upper Devonian clastic sequence of West Virginia have been based on gamma-ray-density logs, cores, and sample studies. In northwestern West Virginia, the Upper and Middle Devonian unit is characterized by interbedded gray and black shales, with the darker shales recognized on gamma-ray logs as zones of increased radioactivity. The overall thickness of the section decreases toward the west whereas the proportion of black shale increases toward the west. The proportional increase in black shale occurs in two ways; there is an increased number of black shale beds in the west, and the thickness of the interbedded gray shales decreases.

The study area extends across the western boundary of the Rome trough, with the presence of this tectonic feature manifested in two ways in the sediments accumulated over the trough. First, there is a pronounced thickening of the sediments into the trough, and second, the Rhinestreet Shale Member of the West Falls Formation and the Huron Member of the Ohio Shale undergo a facies change from black shale west of the trough to gray shale in the trough area. Further, cross sections and isopach maps provide additional evidence that the Rome trough controlled basin configuration in the region and thus influenced sedimentation during the deposition of the Upper and Middle Devonian clastic sequence in northwestern West Virginia.

End_of_Article - Last_Page 1578------------