State | Iowa |
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Name | Dakata and Windrow Formations |
Geologic age | “Mid” Cretaceous; upper Albian-upper Cenomanian |
Lithologic constituents |
Major
Sedimentary > Clastic > Sandstone (Bed)quartzose, very fine to medium grained; medium to very coarse grained, part pebbly to gravelly, locally cemented by iron oxides (Nishnabotna Mbr., Windrow Fm.), gravel, quartz and chert clasts
Sedimentary > Clastic > Mudstone > Shale (Bed)mudstone/shale, light to dark gray, variably silty-sandy, noncalcareous (Woodbury Mbr.)
Minor
Sedimentary > Clastic > Mixed-clastic > Siltstone-mudstone (Bed, Carbonaceous)red, pink, yellow-brown, black
Incidental
Sedimentary > Chemical > Banded-iron-formation (Bed)massive iron ore, silty to sandy (Windrow Fm.)
Sedimentary > Clastic > Siltstone (Bed)siderite (concretions, pedogenic sphaerosiderite pellets, cemented siltstone)
Sedimentary > Coal > Lignite (Bed)
|
References | Witzke, Brian J., Anderson, Raymond R., and Pope, John P., 2010, Iowa Geological and Water Survey, DNR, Bedrock Geologic Map of Iowa, OFM-2010-1. Scale 1:500,000. |
NGMDB product | |
Counties | Adair - Adams - Allamakee - Audubon - Boone - Buena Vista - Butler - Calhoun - Carroll - Cass - Cerro Gordo - Cherokee - Chickasaw - Clay - Crawford - Dallas - Delaware - Dickinson - Emmet - Floyd - Franklin - Greene - Guthrie - Hancock - Harrison - Howard - Humboldt - Ida - Kossuth - Lyon - Mills - Mitchell - Monona - Montgomery - O'Brien - Osceola - Page - Palo Alto - Plymouth - Pocahontas - Pottawattamie - Sac - Shelby - Sioux - Webster - Winnebago - Woodbury - Wright |