THE BANNOCK OVERTHRUST 
683 
members of the Cretaceous system. ‘These portions of the geologic 
column do not outcrop within the area with which this paper 
especially deals and are not included in the generalized section 
which follows. 
GENERALIZED SECTION IN THE REGION OF THE BANNOCK THRUST 
sQuaternary: Alluvium, travertine, basalt flows.............-........ 
Tertiary (Pliocene?): Marls, marly limestone, and calcareous con- 
PIOIMEL ALCS VM RAR ae NTE AM Satna hie ooor..e Seis Siebel Sra eee 
Tertiary (Eocene): Sandstones, conglomerates, and limestones 
Unconformity. 
Cretaceous and Jurassic: 
Beckwith formation (24h) (6a), red shales, sandstones, and con- 
PIOMERAL eS Hen MIR eee Se cer cle adeig ale ba wai eure vss Getsrmente 
Jurassic: Twin Creek limestone (241) (shaly limestone).............. 
Jurassic or Triassic: Nugget sandstone (dark red to white sandstone 
UNG MCIMATEZICE) eee eM omam Cate aici aai hasr a: Acker MU oh Sea 
Triassic: (4) (22) (23) 
Ankareh shale (a red-bed horizon) shales and mottled limestone. . . 
Thaynes limestone, thin-bedded sandy limestone with heavy lime- 
stones (and locally conglomerate at top?)..................-. 
Woodside shale, iron-stained calcareous shale with heavy limestones 
Carboniferous: 
Permian ? 
Phosphoria formation, 75 to 627 ft., averages.............. 
Rex chert member ONO SO ltynp) Aenea rce ace seal e 
Pennsylvanian: 
WVellsitormia Glommn ete aiecs i hue on ae Co unermeieuni ngs. 5h 
Mississippian: 
Limestone, upper Mississippian, light gray, thick-bedded.... 
Madison limestone, lower Mississippian, thin-bedded, dark 
PrAvecouy WiSh=PLay ceva etl eee ee wale aad aia ele cee 
Devonian Jetterson limestone (T4a) (19gb) . 6.00.5. 62 5. os ase. 
Siluniamepeleimestone (aes) TOG) 5 (La) eee eee sacks eee sa elie cigs <te ws cs eeeliote 
Ordovician: (1c) (19c) Quartzite and limestone.................... 
Upper Cambrian: (25) (26) St. Charles limestone (bluish-gray to gray 
arenaceous limestones, with some cherty and concretionary 
layers, passing at the base into thin-bedded gray to brown 
sandstone..... Rr aes sot are yh peta aR yt oe Ge ARCs eater saan Ne 
Middle Cambrian: 
Nounan limestone (light gray to dark lead-colored arenaceous 
IME STONES) REAM eed: bya doin ue acne wn eaerco nec ane ac Tanne nae 
FEET 
4,650 
3,500 
1,900 
670 
2,000 
1,000 
35° 
