188 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
ore, on the other hand, which hes on the Gibson and on the Smuggler 
faults side by side with the polybasite ore, is evidently a replacement or 
impregnation of the dolomite, and does not contain a large amount of barite 
or other gangue material. It seems probable that after the deposition of 
the low-grade ore, but before the cessation of the period of ore formation, 
these east-west fracture zones were formed, and that along these zones 
fresh solutions deposited the polybasite and barite. The native silver 
appears to be a product of alteration from the polybasite. 
Evidence goes to show that subsequent to all the mineralization a fault 
was developed nearly parallel with the Silver fault, but slightly steeper. 
The effect of this fault was to throw the rocks on the west side downward 
and to the north. Thus the original polybasite ore shoot was divided into 
what are now the Mollie Gibson and the Smuggler ore bodies. This fault 
must have also faulted the preexisting faults of the Della system. On this 
supposition the Gibson fault and the Smuggler fault were originally one. 
Measurements show that the Gibson fault narrows going down, its per- 
pendicular separation being about 50 feet in the tenth level of the Mollie 
Gibson and 110 feet in the third. The Smuggler fault, on the other 
hand, has a more important movement with increasing depth, so that 10 or 
15 feet of perpendicular separation in the fourth level of the Della S. 
becomes 70 feet in the ninth level of the Mollie Gibson. There is abun- 
dant evidence of this postmineral faulting below the rich stopes of the 
Mollie Gibson, in breccias containing angular fragments of the ore, often 
cemented by native silver. Mine sections on Pls. XLI and XLII show 
the structure of the Smuggler mine as described. They are taken at oppo- - 
site ends of the mine, one through the shaft and one through the great 
stopes at the end of the Clark tunnel. 
COWENHOVEN TUNNEL. 
The Cowenhoven tunnel starts on the north side of the Roaring Fork 
Valley at the base of Smuggler Mountain and runs under the mountain to 
a point below Hunter Creek Valley. It connects all the mine workings 
along the ore-bearing zone which lie north of the Smugeler mine, and is 
used for transportation and dramage. The tunnel starts in an almost 
easterly direction, and after passing through a considerable thickness of 
glacial drift runs into red and white arenaceous limestones and the gray 
