LATERAL EXTENT OF BURLINGTON KEOKUK AND WARSAW OF THE MISSISSIPPIAN STRATOTYPE AT GRAY QUARRY, ILLINOIS

The Burlington base is a coarse, gray crinoidal unit at House Springs, but missing at Gray Quarry where isostatic rebound created erosion of beds below the Dolbee Creek (White Ledge). The White Ledge is a oolitic limestone capped by a "hardground" of glauconite and the conodont Bactrognathus distortus (Baxter 1984). Above the hardground are 3 coarse beds of lower Haight Creek. The upper Haight Creek is limonitic with 3 coarse units. The coarse white CF/HC marker has silty glauconitic units above and below with the conodont Eotaphrus burlingtonensis (Baxter 1988). The massive Cedar Fork starts with a 5' oolitic base below a glauconitic marker below 8' of mottled cherty Montrose breccia below a disconformity with glauconite and capped with white grainstone. Then Keokuk member has a base of clasts and the conodont Gnathodus texanus (Baxter 1988). The member has 3 coarse white cycles -one thin and 2 thick. The Warsaw member has a dark dolomite base, a limonitic chert and geodes and a thin cap of red paleosol. The units of the stratotype can be traced to Winkleman, AZ, Cadomin, AB and Mount Vernon, KY. Facies become cherty on the western shelf slope, oolitic on the outer craton and dolomite with evaporites in the interior. Red shales are in West Virginia and Pennsylvania. Calcareous sandstones in Michigan, Ohio and Kentucky suggest a European source. Preliminary work in Norway, Ireland, France and Patagonia suggest a distribution much greater than expected.