Arikaree Group (SDTa;0)

Includes: Rosebud Formation (Miocene)- Pink siltstone with channel sandstone and concretions. Thickness up to 250 ft (76 m). Harrison Formation (Miocene)- Gray, silty sandstone and reworked volcanic ash with calcareous siltstone and marl. Thickness 180 ft (55 m). Turtle Butte Formation (Miocene)- Light-green to gray siltstone with sandstone channels containing claystone pebbles. Thickness 65 ft (20 m). Monroe Creek Formation (Oligocene)- Tan to grayish-tan, massive sandy siltstone and reworked volcanic ash. Thickness 100 ft (30 m). Sharps Formation (Oligocene)- Pink siltstone and claystone with concretionary layers, paleochannels, and beds of reworked volcanic ash. Thickness 360 ft (110 m).

State	South Dakota
Name	Arikaree Group
Geologic age	Phanerozoic \| Cenozoic \| Tertiary \| Eocene Oligocene
Original map label	Ta
Primary rock type	siltstone
Secondary rock type	sandstone
Other rock types	claystone; volcanic ash; limestone
Lithologic constituents	Major Sedimentary > Clastic > Sandstone (Bed) Sedimentary > Clastic > Siltstone (Bed) Minor Sedimentary > Carbonate > Marlstone (Bed) Igneous > Volcanic (Volcaniclastic) Sedimentary > Clastic > Mudstone > Claystone (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 coverage	Bennett - Harding - Jackson - Mellette - Pennington - Shannon - Todd - Tripp