GRANITE GNEISS (AGE 2,600 TO 3,100+ Ma)--Layered to massive, locally migmatitic;
     metasedimentary and metavolcanic rocks locally common.  Includes Webb Canyon
     Gneiss in Teton Range.  Wgn
METASEDIMENTARY AND METAVOLCANIC ROCKS--Amphibolite, hornblende gneiss,
     biotite gneiss, quartzite, iron-formation, metaconglomerate, marble, and pelitic
     schist; locally preserved textures and structures suggest origin to be sedimentary or
     volcanic. Older than 2,875 Ma in Teton Range; older than 3,200 Ma in Granite
     Mountains; older than 2,600 Ma in Medicine Bow Mountains and Sierra Madre, where it is
     the Late Archean Phantom Lake Metamorphic Suite 3.  WVsv
  Metasedimentary rocks
    Wind River Range--Metagraywacke, pelitic schist, metaconglomerate, graphitic schist, and
       iron-formation; local meta-andesite.  At least 2,800 Ma.  Ws
    Seminoe Mountains (southeast end of Granite Mountains)--Pelitic schist, quartzite, and
       iron-formation.  Ws
    Casper Mountain (northwest extension of Laramie Mountains)--Felsic gneiss, quartzite, and
       iron-formation.  Ws
    Laramie Mountains--Pelitic schist, iron-formation, quartzite, marble, metaconglomerate,
       and metagraywacke.  Ws
  Metamorphosed mafic and ultramafic rocks
    Teton Range--Rendezvous Metagabbro; 2,875 Ma or older.  Wmu 
    Gros Ventre Range--Hornblende gneiss and serpentinite.  Wmu
    Wind River Range--Pillowed amphibolite, metagabbro, and ultramafic sills.  Wmu
    Wind River Canyon (cutting through Owl Creek Mountains)--Amphibolite and felsic
       gneiss of volcanic origin.  Older than 2,700 Ma.  Wmu
    Bighorn and Granite Mountains--Amphibolite.  Wmu
    Seminoe Mountains--Amphibolite of volcanic origin, komatiite, and metagabbro.  Wmu
    Casper Mountain--Amphibolite and serpentinite.  Wmu
    Laramie Mountains--Amphibolite of volcanic origin, komatiite(?), metagabbro, and
      ultramafic sills.  Wmu
PERIDOTITE INTRUSIVE ROCKS--In Laramie Mountains.  Wp
GRANITIC ROCKS OF 2,600-Ma AGE GROUP
  Yellowstone National Park--Granite.  Wg
  Teton Range--Mount Owen Quartz Monzonite.  Age 2,500+/- Ma; may be of Early Proterozoic
     age.  Wg
  Gros Ventre and Washakie Ranges--Granitic rocks.  Wg
  Owl Creek, Granite, and Seminoe Mountains, Rawlins uplift, and Medicine Bow Mountains--
     Granite.  Wg
  Wind River Range--Granodiorite to porphyritic and equigranular granite.  Wg
  Sierra Madre--Granite and granodiorite.  Wg
  Laramie Mountains--Granite, amphibolite, and minor amounts of metasedimentary rocks.  Wg
  Hartville uplift--Granite and quartz monzonite.  Wg
  Black Hills uplift--Granite and minor amounts of metasedimentary rocks.  Wg
GRANODIORITE OF THE LOUIS LAKE PLUTON (AGE 2,640 Ma)--Equigranular; locally
     gneissic.  Wgd
QUARTZ MONZONITE OF NORTHERN YELLOWSTONE (AGE 2,740 Ma).  Wqm
PLUTONIC ROCKS
  Wind River Range--Largely granite gneiss; contains diorite and quartz diorite facies.  WVg
  Bighorn Mountains--Quartz diorite to quartz monzonite.  Age 2,900+ Ma.  WVg