Upper Miocene Rocks

Southwest Wyoming: South end of Wind River Range--Siliceous, arkosic, and locally radioactive sandstone, claystone, and conglomerate. Fission-track age about 27 Ma. Recent work suggests that part of these deposits may be of Eocene age. Pliocene and Miocene (as originally defined 2) South Pass Formation. Saratoga Valley--White to greenish-gray tuffaceous sandstone, siltstone, and claystone; locally conglomeratic. North Park Formation; Central Wyoming: Arkosic sandstone, conglomerate, and siltstone; some light-colored tuffaceous radioactive claystone and white cherty limestone. North of Sweetwater River in Granite Mountains--Light-colored tuffaceous radioactive claystone, siltstone, sandstone, and arkose. Moonstone Formation; East Wyoming: Light-colored tuffaceous claystone, sandstone, and conglomerate. Ogallala Formation in Denver Basin.
State Wyoming
Name Upper Miocene Rocks
Geologic age Upper Miocene
Lithologic constituents
Sedimentary > Clastic > Sandstone
Sedimentary > Clastic > Mudstone > Claystone (Tuffaceous)
Sedimentary > Clastic > Conglomerate
Sedimentary > Carbonate > Limestone
Igneous > Volcanic (Pyroclastic-tuff)
Sedimentary > Clastic > Siltstone
NGMDB product
Counties Albany - Carbon - Converse - Crook - Fremont - Goshen - Laramie - Natrona - Platte - Sublette