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Middle and Lower Eocene Rocks

MIDDLE AND LOWER EOCENE ROCKS--Equivalent to Aycross (Ta) and Wind River (Twdr) Formations. AYCROSS FORMATION (ABSAROKA VOLCANIC SUPERGROUP: THOROFARE CREEK GROUP)--Brightly variegated bentonitic claystone and tuffaceous sandstone, grading laterally into greenish-gray sandstone and claystone. In and east of Jackson Hole contains gold-bearing lenticular quartzite conglomerate. WIND RIVER FORMATION--Variegated claystone and sandstone; lenticular conglomerate.
State Wyoming
Name Middle and Lower Eocene Rocks
Geologic age Phanerozoic | Cenozoic | Tertiary | Eocene-Early Eocene-Middle
Comments COMU shows age with large arrow bar in both directions in Eocene.
Primary rock type mixed clastic/volcanic
Secondary rock type fine-grained mixed clastic
Other rock types medium-grained mixed clastic
Lithologic constituents
Map references
Love, J.D. and Christiansen, Ann Coe, 1985, Geologic Map of Wyoming: U.S. Geological Survey.
Unit references
Love, J.D. and Christiansen, Ann Coe, 1985, Geologic Map of Wyoming: U.S. Geological Survey.
Counties Fremont