84 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
an east-west trend and a flat southerly dip, therefore belong to a somewhat 
later period than the Aspen Mountain system. 
Sixth. On East Aspen Mountain there are found the representatives of 
a system of north-south and in general vertical faults, which has its maim 
development in Tourtelotte Park. From this point of maximum develop- 
ment the system dies out to the north and to the south. So far as can be 
judged it is entirely later than the ore deposition, and therefore later than 
the Della system. The Clark fault on Smuggler Mountain may be included 
in this last system. 
TOURTELOTTE PARK SPECIAL MAP. 
The general attitude of the formations on Aspen Mountain undergoes 
a marked change to the southward, so that the strike changes from east to 
northeast and finally swings round and becomes permanently north. This 
change is evidently antecedent to the faulting which forms such a conspicu- 
ous part of the geology in this region. The main features of-folding are 
the same in the Tourtelotte Park district as in Aspen Mountain, but they 
are less accentuated. The deep broken syncline of Aspen Mountain is 
continuous into the north end of the Tourtelotte Park special area, but 
becomes continually shallower toward the south, until at about the 
southern end of the Tourtelotte Park mining district it has virtually 
disappeared. The flattening of the beds on East Aspen Mountain is also 
continuous into the Tourtelotte Park district, where it is developed into 
an anticline, which is in many places obscured by subsequent faulting. 
There also appears in the Tourtelotte Park area a second syncline to the 
east of the anticline, which lies next the granite; but in many places this 
syncline has been uplifted by faulting and removed by erosion. These 
gentle folds become less marked toward the south, and finally die out. The 
line of the Castle Creek fault is not strictly parallel with that of the contact 
of granite and sedimentary rocks, but the two lmes converge toward the 
south, so that the width of the belt occupied by the lower stratified rocks 
becomes continually less. The rocks to the west of the Castle Creek fault 
have an entirely independent structure, so that the gentle anticline and 
syncline referred to are gradually cut out by the encroachment of the 
Castle Creek fault. The main anticline, whose axis practically coincides 
with the divide between Roaring Fork and Castle Creek throughout the 
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