THE BANNOCK OVERTHRUST 
fold of the structure sec- 
tion may represent the 
-source of the overthrust 
mass of these formations 
that lies some 12 miles 
to the east. The source 
can certainly not be 
nearer, for the Missis- 
sippian limestones do 
not rise to the level of 
the fault plane in any of 
the folds farther east in 
this district. Further- 
more, the size’ of the 
Mississippian limestone 
mass, as inferred from 
known conditions north 
and south of the line of 
the section, suggests 
that either the western- 
most fold of the section 
has not been made 
large enough, or that 
the source was a more 
westerly fold. These 
considerations make it 
apparent «that the 
amount of horizontal 
displacement is not less 
than 12 miles. 
Another measurement 
of the horizontal dis- 
placement may be ex- 
pressed by a line drawn 
perpendicular to the 
general trend of the 
fault trace and extend- 
ing from the western- 
most point on the trace 
The direction of view is northwesterly. The southern 
Fic. 4.—Panorama from point near the southeast corner of area shown in Fig. 2. 
793, 
, together with the approximate character 
he position of the subordinate branch fault 
tip of the uneroded portion of the overthrust block and t 
For meaning 
1 anticlines are visible in the foreground (in the Twin Creek limestone). 
of geologic discordance is indicated, A syncline and paralle 
of letter symbols see Fig. 1, 
