THE HART MOUNTAIN OVERTHRUST 51 
There is nothing sufficiently regular about the dip of the fault 
plane to indicate the direction of movement. The fact, however, 
that the Cretaceous and Tertiary rocks in the Bighorn Basin to the 
east are continuous and but slightly disturbed for nearly too miles 
indicates plainly enough that the faulted block did not come from 
the east. The thick cap of volcanics to the west makes it impos- 
sible to expect any evidence in that direction, but in spite of that 
is seems clear enough that this block moved from west to east. 
The South Fork thrust.—Along the lower valley of the South 
Fork of Shoshone River a second thrust fault is exposed on both 
sides of the valley, below the Hart Mountain thrust already 
described. As far as this fault could be traced, Sundance was 
found resting on Cody or Fort Union(?), and a section from the 
river level to the top of the ridge on the south side of the valley 
reveals the following situation: 
Top 
Madison 
-2e. Major thrust 
Fort Union( ?) 
Cody 
Frontier 
Thermopolis and Mowry 
Cloverly 
Morrison 
Sundance 
a.) «Minor thrust 
Cody 
Bottom 
On the north side the section is as follows: 
Top 
Madison 
ee Vajyorthrust 
Frontier 
Thermopolis and Mowry 
Cloverly 
Morrison 
Sundance 
. . . . Minor thrust 
Cody 
Bottom 
