ROCKY MOUNTAIN STRUCTURE IN IDAHO 453 
topographic sags and laps up on the west side of the adjoining hills. 
The upper fault block is composed of Cambrian and Ordovician 
formations, comprising the east limb of a syncline. ‘The rock slices 
in the fault zone include at least a broken syncline of Ordovician 
EXPLANATION 
Alluvium 
UNCONFORMITY 
Salt Lake formation 
UNCONFORMITY 
cene cenefRecent 
Wasatch formation 
UNCONFORMITY 
oO 
a 
Wells formation 
Cc 
Brazer limestone 
CONFORMITY 
p 
c 
z 
Upper Missts- ee TUnsy ae o- Plio- 
Devonian stppian yan 
| 
Ga 
oa 
Threeforks limestone 
UNCONFORMITY 
2) 
Qo 
SILUR- DEVON- CARBONIFEROUS 
1AN 
Lak 
n dolomite 
REN 
Fish Haven dolomite 
UNCONFORMITY 
@ 
iy 
2 
4, 
a 
ORDOVICIAN 
Swan Peak quartzite 
estone 
_ 
33 
Exe) 
ZC 
ae 
ie) 
Garden 
8 UNC 
estone 
8 St Charles 
ite member) 
VY Worm Creek qua 
v3 
Nounan |i 
YW 
Bloomington formation 
(Hodges s ale member) 
stone 
3 
rn) 
IN 
1 ’ (°) 1 2 3 Miles 
are ess =— — met ce 
— “Bannock Overthrv x 
5 S Brigham quartzite 
S lrician Gl 
Fic. 5.—Map with geologic structure section of part of the Bear River Range, 
Montpelier quadrangle, showing the complex fault zone of the Bannock overthrust. 
formations and parts of other folds containing Devonian and 
Carboniferous formations. The easternmost rock slice of the zone 
is probably composed of Fish Haven dolomite (Upper Ordovician). 
The structures east of the fault zone, along the line of structure 
section ZZ’, are concealed by Tertiary beds and alluvium, but 
- farther north scattering outcrops of the Wells formation (Pennsyl- 
vanian) occur east of this zone. It is thought, therefore, that the 
QUATERN- 
ARY 
TERTIARY. 
JAN 
CAMBRIAN 
