86 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
and complicated. Once past the line of contact, however, we have no 
method of ascertaining the number, system, or amount of throw of these 
faults, or any positive proof of their existence, so that the faulted area to 
be studied must be considered as essentially comprised between the Castle 
Creek fault and the granite-quartzite contact . 
The amount of disturbance which has taken place in this area, as 
indicated by the occurrence of these numerous intersecting faults, is appar- 
ently greater in the northern part of the Tourtelotte Park special tract, or 
in about the area occupied by the Tourtelotte Park mining map (Atlas 
Sheet XX1), than in any other part of the entire district examined in the 
course of the survey. The southern part of the Tourtelotte Park special 
tract has a similar but somewhat less complicated system of faulting, and 
the two halves of the tract may be conveniently considered as representing 
slightly differmg areas. These two areas may be separated at the line of 
the Butte fault, which traverses the whole district from east to west. 
The faults of the northern half show a continuation of the characteris- 
tics of those of Aspen Mountain, together with the development of new 
features. The most characteristic of the Aspen Mountain faults gradually die 
out in the Tourtelotte Park district, while faults which are unimportant on 
Aspen Mountain, or which are even totally absent, become well marked and 
important in Tourtelotte Park. Thus the great north-south break called 
the Pride fault, which on Aspen Mountain splits into two branches, dimin- 
ishes in importance gradually toward the south, so that the throw becomes 
comparatively slight in the Tourtelotte Park district. On the other hand, 
there is another system of north-south faults, which is parallel with the 
system of the Pride and the Saddle Rock, but which has its greatest devel- 
opment in Tourtelotte Park and becomes continually less important toward 
the north, finally dying out or merging into the Silver fault. To this class 
belong the Justice and Copper faults, also the Ontario and other parallel 
breaks which are exhibited to the east of the Copper fault. This second 
system is apparently younger than the system represented by the Pride, 
Sarah Jane, and allied faults. It is evident that the former system has 
developed mainly subsequent to the period of mineral deposition, while 
the Pride or Aspen Mountain system must have been nearly completed 
before the deposition of the ores, since it is along these faults that the ores 
are most conspicuously formed. The younger system, however, which is 
