Kootenai and Morrison Formations and Ellis Group

Kootenai Formation - Rusty thin-bedded sandstone, grayish-red soft claystone, white limestone, and chert-pebble conglomerate. Morrison Formation (Northern Yellowstone area) - Variegated silty claystone and fine-grained sandstone. Ellis Group - includes Swift, Rierdon, and Sawtooth Formations. Swift Formation - Calcareous glauconitic sandstone and sandy limestone. Rierdon Formation - Mudstone, siltstone, shale, and basal limestone. Sawtooth Formation - Red beds and limestone.
State Wyoming
Name Kootenai and Morrison Formations and Ellis Group
Geologic age Middle Jurassic-Lower Cretaceous
Lithologic constituents
Major
Sedimentary > Carbonate > Limestone
Sedimentary > Clastic > Mudstone > Claystone
Sedimentary > Clastic > Sandstone
Minor
Sedimentary > Clastic > Mudstone > Shale
Sedimentary > Clastic > Conglomerate
Sedimentary > Clastic > Siltstone
Sedimentary > Clastic > Mudstone
References
NGMDB product
Counties Park