Qp
Pediment gravel (Holocene? and Pleistocene)
Kcol
Colorado Group, lower part, undivided (Lower Cretaceous)
QTp2
Older pediment gravel, higher level where more than two adjacent levels overlie bedrock (Pleistocene and Pliocene)
Qa
Alluvium (Holocene)
Kk
Kootenai Formation (Lower Cretaceous)
KJm
Morrison Formation (Lower Cretaceous and Jurassic)
Js
Swift Formation (Upper Jurassic)
Pa
*a
Amsden Formation (Pennsylvanian)
Mt
Tyler Formation, undivided (Upper Mississippian)
Mh
Heath Formation (Upper Mississippian)
Mo
Otter Formation (Upper Mississippian)
Mk
Kibbey Formation (Upper Mississippian
Mm
Mission Canyon Limestone (Upper and Lower Mississippian)
EObhqm
#bhqm
Biotite hornblende quartz monzonite (Eocene)
Qac
Alluvium and colluvium, undivided (Holocene)
Ml
Lodgepole Limestone (Lower Mississippian)
Dj
Jefferson Formation (Upper Devonian)
EObhd
#bhd
Biotite hornblende dacite (Eocene)
Cpi
_pi
Pilgrim Formation (Upper Cambrian)
w
Open water
EOqm
#qm
Quartz monzonite (Eocene)
Cf
_f
Flathead Sandstone (Middle Cambrian)
Cpmw
_pmw
Park Shale (Upper and Middle Cambrian), Meagher Limestone (Middle Cambrian), and Wolsey Formation (Middle Cambrian), undivided
DCm
D_m
Maywood Formation (Upper and Middle Devonian) and locally Upper Cambrian beds
Qgt
Glacial till (Pleistocene)
Xbg
Biotite gneiss (Paleoproterozoic)
Xpd
Pinto Diorite (Paleoproterozoic)
MDt
Three Forks Formation (Lower Mississippian and Upper Devonian)
Xd
Diorite (Paleoproterozoic)
Cw
_w
Wolsey Formation (Middle Cambrian)
Cm
_m
Meagher Limestone (Middle Cambrian)
Cp
_p
Park Shale (Upper and Middle Cambrian)
Xag
Augen gneiss (Paleoproterozoic)
Cpp
_pp
Pilgrim Formation (Upper Cambrian) and Park Shale (Upper and Middle Cambrian), undivided
Mb
Big Snowy Group, undivided (Upper Mississippian)
EOg
#g
Granite (Eocene)
mt
Mine tailings (Holocene)
Qoa
Old alluvium (Holocene and Pleistocene)
EOrp
#rp
Rhyolite porphyry (Eocene)
Qt
Terrace gravel (Holocene and Pleistocene)
Qc
Colluvium (Holocene)
Qgty
Glacial till, younger till where more than one age of till is recognized (Pleistocene)
Xgg
Granite gneiss (Paleoproterozoic)
Ql
Landslide deposit (Holocene and Pleistocene)
QTp1
Older pediment gravel, lowest level where two or more adjacent levels overlie bedrock (Pleistocene and Pliocene)
Mlb
Lodgepole Limestone, biohermal limestone (Lower Mississippian)
Mts
Tyler Formation, sandstone beds in lower and middle parts (Upper Mississippian)
QTg
Older gravel (Pleistocene and Pliocene)
Xa
Amphibolite (Paleoproterozoic)
Ynei
Neihart Quartzite (Neoproterozoic)
Jp
Piper Formation (Middle Jurassic)
Pq
*q
Quadrant Formation (Pennsylvanian)
Xgda
Gneissic granodiorite and amphibolite, undivided (Paleoproterozoic)
Wd
Metadiorite (Neoarchean)
Yc
Chamberlain Formation (Mesoproterozoic)
EOsn
#sn
Shonkinite (Eocene)
Yn
Newland Formation (Mesoproterozoic)
Qog
Old gravel (Holocene? and Pleistocene)
QTp3
Older pediment gravel, highest level where more than two adjacent levels overlie bedrock (Pleistocene and Pliocene)
EOdi
#di
Biotite diorite (Eocene)
OGb
@b
Basalt (Oligocene)
MIOGs
!@s
Sedimentary rocks, undivided (Miocene and Oligocene)
OGs
@s
Sedimentary rocks older than basalt flow (Oligocene and Eocene?)
QTl
Older landslide deposit (Pleistocene and Pliocene?)
Yg
Greyson Formation (Mesoproterozoic)
Tbg
Boulder gravel (Miocene?)
Du
Upper and Middle Devonian rocks, undivided
Kfr
Fall River Formation (Lower Cretaceous)
Kmt
Mowry Shale and Thermopolis Shale (Lower Cretaceous), undivided
Ys
Spokane Formation (Mesoproterozoic)
Kfl
Frontier Formation, lower part (Lower and Upper? Cretaceous)
MIOGf
!@f
Fort Logan Formation (Miocene and Oligocene)
Kfb
Frontier Formation, Big Elk Sandstone Member (Upper Cretaceous)
KJme
Morrison Formation (Lower Cretaceous and Jurassic) and Ellis Group (Jurassic), undivided
Kc
Cody Shale (Upper Cretaceous)
Ktc
Telegraph Creek Formation (Upper Cretaceous)
QTp
Older pediment gravel, undivided (Pleistocene and Pliocene)
Mmu
Madison Group, undivided (Upper and Lower Mississippian)
OGEOrb
@#rb
Rhyolite with breccia blocks of Paleozoic rocks (Oligocene? or Eocene)
POMIg
~!g
Gravel and interbedded finer clastic strata (Pliocene and Miocene?)
EOd
#d
Dacite (Eocene)
EOm
#m
Monzonite (Eocene)
Ke
Eagle Sandstone (Upper Cretaceous)
Cu
_u
Upper and Middle Cambrian rocks, undivided
PMab
*Mab
Amsden Formation (Pennsylvanian) and Big Snowy Group (Upper Mississippian), undivided
EOlwt
#lwt
Lithic welded tuff (Eocene)
Kcl
Claggett Formation (Upper Cretaceous)