Figure 4. Distribution of channelized Lower Skinner sandstone in northeastern and north-central Oklahoma. This map includes data from: Astarita (1975), Chandler (1977), Cockrell (1985), Cole (1968), Lojek (1984), Pulling (1979), Shipley (1977), Siemers (2003), Shulman (1966), Valderrama (1976), and Verish (1979).