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Mineral Resources On-Line Spatial Data

Ogallala Group

Includes: Ash Hollow Formation- White, tan, and gray, well-cemented, calcareous sandstone and silty limestone often referred to as "mortar beds". Thickness 90-250 ft 27-76 m) Valentine Formation- Gray, unconsolidated, fine- to coarse grained, fluvial siltstone, channel sandstone, and gravel derived from western sources. Thickness 175-225 ft (53-69 m). Fort Randall Formation- Pink and gray claystone with interbedded sandstone. Also includes green to gray orthoquartzite, bentonitic clay, and conglomerate. Thickness up to 130 ft (40 m).
StateSouth Dakota
NameOgallala Group
Geologic agePhanerozoic | Cenozoic | Tertiary Quaternary | Miocene Pliocene(?) Pleistocene-Early
Original map labelTo
CommentsAlso includes the Thin Elk, Bon Homme, Herrick, Medicine Root, and "western derived" gravels.
Primary rock typesandstone
Secondary rock typesiltstone
Other rock typesclaystone; limestone; gravel; clay or mud; conglomerate
Lithologic constituents
Major
Sedimentary > Carbonate > Limestone (Bed)
Sedimentary > Clastic > Mudstone > Claystone (Bed)
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Sandstone (Bed)
Minor
Sedimentary > Clastic > Conglomerate (Bed)
Map references
Martin, J. E., Sawyer, J. F., Fahrenbach, M. D., Tomhave, D. W., and Schulz, L. D., 2004, Geologic Map of South Dakota: South Dakota Geological Survey
Unit references
Martin, J. E., Sawyer, J. F., Fahrenbach, M. D., Tomhave, D. W., and Schulz, L. D., 2004, Geologic Map of South Dakota: South Dakota Geological Survey
Geographic coverageBennett - Bon Homme - Brule - Charles Mix - Corson - Gregory - Jackson - Lyman - Mellette - Shannon - Todd - Tripp - Yankton

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