ASPEN SPECIAL MAP. (5 
movement has been to the southeast on the south side, the direction havy- 
ing been at an angle of 45 degrees to the horizontal on the fault plane. 
The perpendicular separation of corresponding beds is about 150 or 200 
feet, and this separation is traceable in mine workings from top to bottom 
of the hill, for the dip of the fault is only slightly greater than the slope of 
the hill. Its outcrop can not be actually observed on the ground, for at 
this point there is a very thick covering of morainal material. The line 
represented on the map (Atlas Sheet XXVII) is calculated from the 
underground workings. The fault is represented on the map as dying 
out in the red Maroon sandstones, and this it probably does sooner or 
later. There are several slips parallel to the Della fault and having the 
same sort of motion, but in none of these is any great displacement 
observable. The Smuggler fault, however, which lies a short distance 
south of the Della, appears to become quite important in the lower part 
of the Smuggler and in the Mollie Gibson mine. 
The age of the Della fault, and of the smaller faults which are 
parallel with it, is indicated by the phenomenon of ore deposition. The 
chief ore shoots throughout the mountain are found at the intersection of 
the Silver fault with the Della fault and other faults of this system, where 
the Silver fault is cut off by the flatter fault above. This persistent and 
conspicuous influence of the Della system of faults upon the distribution 
of the ore shows that these faults existed prior to the ore deposition. On 
the fault planes, however, as has been especially well observed in the case 
of the Deila fault, there is often found crushed and broken ore, while most 
of the rock along these planes is entirely barren and shows no evidence 
that any ore has been formed there in place. The mine managers find, 
moreover, that the motion along the Della system of faults is still going 
on, as shown by the deformation of mine workings. The combination of 
these facts leads to the inference that while the Della system of faults 
existed previous to the ore deposition, the motion went on after the forma- 
tion of the ores; so that in the case of the Della fault probably a large, 
if not the larger, part of its motion was postmineral. 
Clark fautt—In the Mollie Gibson and Smuggler mines there is evidence 
that the ore bodies, together with the inclosing rocks and all previously 
formed features, have been extensively faulted by a comparatively recent 
movement. The evidence of this faulting is fairly conspicuous in these 
