92 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
In the southern part of the area of the Tourtelotte Park special map 
the effect of this elevation of the beds on the west side of the fault and 
the corresponding depression of the beds on the east side is to diminish the 
throw very rapidly toward the south. Thus the amount of displacement 
near the southern end of the area appears to be about 2,600 feet (see Sec- 
tion F, Aspen district map, Atlas Sheet VII); in Queens Gulch the dis- 
placement is about 6,300 feet; while at the northern end of the area it is 
probably as high as 8,000 feet (see Section D, Aspen district map). 
The diminishing of the Castle Creek fault is accompanied by a corre- 
sponding dying out in intensity of the associated folding. The close 
overthrown fold which is shown at Castle Butte and at the western base of 
Aspen Mountain becomes progressively more open toward the south, and 
the easterly dip of the overturned beds becomes progressively steeper. In 
Keno Gulch the red sandstones dip toward the east at an angle of 45 
or 50 degrees; in Ophir Gulch, however, the beds dip east at an angle of 
about 70 degrees. At about the point where the fault enters Queens 
Gulch the beds become actually perpendicular; southward from this point 
they assume a westerly dip, thus marking the end of the overthrown fold; 
and from this point on the beds lie in their normal succession, always 
dipping to the west at an angle which grows less toward the south. The 
close overthrown fold of Aspen Mountain is thus replaced by an extensive 
open fold, several miles in width. The fact that the fold shows sions of 
dying out in the lower formations and becoming more complicated in the 
upper ones, being very much less in the lower Maroon and Weber beds of 
Queens Gulch and vicinity than in the Cretaceous beds of Red Butte, may 
indicate that in the original fold the amount of deformation was greater in 
the upper beds than in the lower throughout the whole of the district, and 
that if erosion in the vicinity of Red Butte should reveal the underlying 
formations corresponding to those exposed in the vicinity of Queens Gulch 
there would appear in these formations a much simpler foldmg than occurs 
in the beds actually exposed. From this point of view the beds west of 
the Castle Creek fault form an overthrown fold, whose axis pitches north- 
ward. Erosion, acting more vigorously on the uplifted portion, has stripped 
the fold fault down to near its roots in the southern part of the district 
mapped, and quite down to its roots where the fold and fault merge into 
the granite at a point not far south of the limits of the map. 
