ENID- Mainly shale with many layers of limestones that pinch out southward, where fine-grained arkosic sandstones are thicker and more numerous. Near Kansas border, sequence is (descending): "Herington Limestone" (20 feet thick) at top, "Enterprise Shale" (45 feet thick), "Winfield Limestone, "IPowi (8 feet thick), "Gage Shale" (80 feet thick), "Towanda Limestone" (3 feet thick), "Holmesville Shale" (25 feet thick), "Fort Riley Limestone," IPofr (30 feet thick) and underlying Florence Flint, IPofr (8 feet thick), "Blue Springs Shale" (60 feet thick), "Kinney Limestone" (5 feet thick), "Wymore Shale" (22 feet thick), "Wreford Limestone," IPowr (25 feet thick), "Speiser Shale" (38 feet thick), "Funston Limestone (4 feet thick), "Blue Rapids Shale" (15 feet thick), "Crouse Limestone" (6 feet thick), "Easly Creek Shale" (12 feet thick), "Bader Limestone" (5 feet thick), "Stearns Shale" (10 feet thick), "Morrill Limestone" (2 feet thick), "Florena Shale" (6 feet thick), "Cottonwood Limestone," IPoc (3 feet thick), "Eskridge Shale" (6 feet thick), and "Neva Limestone" (25 feet thick) at base. Total thickness, about 400 feet. OKLAHOMA CITY- Red-brown to gray shale and orange-brown fine-grained, crossbedded sandstone; grades southward into arkosic sandstone and conglomerate. Includes "Herington Limestone" at top inPayne County, "Neva Limestone" (0.2 to 1.2 feet thick) at basein Lincoln County, and "Hart Limestone" (4 to 10 feet thick)at base in Pottawatomie County. In Payne County, includesthin stringers of "Winfield Limestone," IPowi (75 feet belowtop), "Fort Riley Limestone," IPofr (245 feet below top),"Wreford Limestone," IPowr (345 feet below top), and"Cottonwood Limestone," IPoc (525 feet below top). Thickness ranges from 300 feet in south to 600 feet in north. LAWTON- Shale, sandstone, and arkose, 300 to 500 feet (90 to 150 m) thick, base covered. ARDMORE-SHERMAN- Shale, red-brown to gray, with arkosic sandstones and limestone conglomerates near Arbuckle Mountains; "Hart Limestone" at base; thickness, 300 to 500 feet, decreasing southeastward. (Pontotoc Group).