Named a member (1 of 6 named members) of Savanna sandstone. Savanna is 1 of 5 named formations used in place of Winslow formation. [Preferred status for Winslow as result of this study not clearly stated.] Probably named for town of Spiro, Le Flore Co, CO, Arkoma basin. Caps ridge in secs 13 and 14, T9N, R25E, just north and northeast of Spiro in area mapped by Thom (unpublished). No type locality designated. Area of this report in Muskogee Co, OK on Chautauqua platform. In a composite section of Savanna sandstone in northern part of Muskogee Co, Spiro sandstone member shown as consisting of thinly bedded, argillaceous sandstone 10 ft thick; separated from underlying Sam Creek limestone member of Savanna by 3 ft of buff shale; separated from overlying Bluejacket sandstone member of Savanna by 45+ ft of black shale and Cavanal coal. In a composite section of Savanna in southern part of Muskogee Co, Spiro shown as consisting of regularly bedded, blocky, fine- to medium textured, brown sandstone 12 ft thick; contains plant fossils west of Porum; separated from underlying Keota sandstone member (new) of Savanna by 50 ft of brown, sandy shale; separated from overlying Bluejacket sandstone member of Savanna by (ascending) 60 ft of brown shale, 10 inches of Cavanal coal, and 50 ft of brown, micaceous, sandy shale. Underlying and overlying shales are unnamed and are part of the Savanna. Columnar section. Stratigraphic table. Of Early Pennsylvanian age.

Source: GNU records (USGS DDS-6; Denver GNULEX).