TOURTELOTTE PARK SPECIAL MAP. 107 
3. The first system of north-south faults —T he overthrust fold described above cul- 
minated in a great fault along its axis, called the Castle Creek fault. This 
fault varied in magnitude, as did the preexisting fold, being greatest in 
the upper beds, diminishing in the lower, and probably dying out in 
the granite. With depth, also, the easterly dip steepened, and finally, 
as shown in the southern part of the Tourtelotte Park special map (Atlas 
Sheet XII), became practically vertical. Probably at about the same time 
with the Castle Creek fault other parallel displacements occurred, the 
ereatest naturally being close to the master fault. The most notable are 
the north-south faults of West Aspen Mountain, which have a heavy throw, 
while the parallel breaks farther to the east have progressively slighter 
displacement. There was also developed, probably at about this time, a 
series of cross fractures, running east and west between the main north- 
south faults, but the rocks do not seem to have had any great movement 
along these east-west planes till a later date. 
The movements which have been thus summarized, together with 
some complications which need not be mentioned here, all occurred 
previous to the deposition of ore, as is shown by the fact that ore solutions 
have chosen them by preference as loci for the mineralization. They may 
be conveniently separated from the succeeding movements which are about 
to be enumerated, and which took place subsequent to the deposition of 
the ore, and may be classified as premineral, while the later movements 
are postmineral. 
4. Postmineral movement.—Subsequent to the period of ore deposition there 
was a movement along certain north-south fractures which had originated, 
probably, at the same time as the north-south faults on West Aspen 
Mountain. This postmineral movement produced, chiefly, the Tourtelotte 
Park north-south fault system, of which the Justice, the Copper, and 
the Ontario faults are examples. 
5. Post-Glacial movement —A continuation of the movement made itself mani- 
fest in the east-west fractures, which also probably originated at an early 
date, but did not attain any great importance until this later period. 
This movement, a large part of which was brought about in post-Glacial 
time, gives rise to the system of east-west faults, of which there are 
numerous examples in the northern half of the Tourtelotte Park special 
area. 
