TOURTELOTTE PARK SPECIAL MAP. 97 
Section D, Atlas Sheet XIII). On Section B to the north and Section E 
to the south an equal apparent displacement is exhibited, the downthrow 
measuring about 800 feet. Between Sections B and D there is appar- 
ently a block in which the Ontario fault is not developed. This block 
lies between the Buite fault and the next east-west fault to the north. This 
east-west fault is apparently a continuation of the Good Thunder fault of 
Tourtelotte Park, but has a much greater throw. On the south side of this 
block, however, the outcrop of the Ontario fault reappears in exactly the 
same line, with the same amount and direction of throw as on the north 
side. There can, therefore, be no doubt that it is the same fault. The reason 
why the fault does not outcrop in the block above referred to is not quite 
evident. Exposures are not very abundant in this intervening space, but 
so far as they are present they seem to consist entirely of granite, which 
shows that the Ontario fault is probably absent. It is possible, however, 
that the fault may actually exist with a diminished or locally altered dis- 
placement. 'To the north of Section B the fault may be continuously traced 
out of the area of the Tourtelotte Park special map into that of the Aspen 
special map, where it is found running nearly along the crest of Hast Aspen 
Mountain. Between Sections B and A, however, the single fault seems to 
split into several parallel faults, which divide up the total throw between 
them, so that in Section A the displacement of that fault which is apparently 
the continuation of the main Ontario fault entails only about 100 feet down- 
throw to the east. In the same sections, however, there appears a second 
parallel fault, farther to the east, which is evidently closely associated with 
the main fault. This second fault has a downthrow to the east of about 500 
feet, so that the two together make up a downthrow of about 600 feet, which 
is the displacement that might naturally be expected. Farther to the north 
there appear (still in the area shown on the Tourtelotte Park special map) 
three such faults, which are continuous into the area of the Aspen special 
map. In that area these faults rapidly die out, and their displacement is 
additionally complicated by east-west cross faults. In the blocks produced 
by the intersection of these cross faults with the main north-south faults the 
disturbance has often brought about tilting, reduction of the amount of dis- 
placement, or even reversal of the normal movement. These disturbances 
“tend to counteract each other, so that on the north edge of the crest of East 
Aspen Mountain the aggregate displacement has become comparatively 
MON XXXI-——7 
