Miocene Rocks

Southwest Wyoming: Southern Rock Springs uplift--Pale-green to tan tuffaceous sandstone and claystone of Miocene(?) age. Conglomerate of uncertain correlation locally at base. Saratoga Valley and west and southwest to Colorado--White massive soft tuffaceous sandstone and lesser amounts of white marl; lower part conglomeratic. Underlies North Park Formation in Saratoga Valley. To the west and southwest is called Browns Park Formation. Rawlins area--White massive soft tuffaceous sandstone; Central Wyoming: White soft tuffaceous sandstone. Locally derived conglomerate in upper and lower parts of sequence; in places lower conglomeratic sequence may be of Oligocene age. In Granite Mountains K/Ar age of tuff in lower part of sandstone sequence about 17 Ma and fission-track age of lower conglomerate about 24 Ma.
State Wyoming
Name Miocene Rocks
Geologic age Miocene
Lithologic constituents
Sedimentary > Clastic > Sandstone (Tuffaceous)
Unconsolidated > Marl
Sedimentary > Clastic > Conglomerate
Igneous > Volcanic (Pyroclastic-tuff)
Sedimentary > Clastic > Mudstone > Claystone
Sedimentary > Carbonate > Marlstone
NGMDB product
Counties Carbon - Fremont - Natrona - Sweetwater