194 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
nearly at right angles with the main shoots. Except along these zones the 
Silver fault is practically barren. 
Pl. XLII, C, is a cross section through the Bushwhacker mine and 
through the southern part of the Park-Regent mine, which lies at this 
point above the Bushwhacker on the Silver fault. The features which 
have been described in the Bushwhacker mine will be seen in this section, 
while those which belong to the Park-Regent will be next described. 
PARK-REGENT MINE. 
The nature of the Silver fault in the Park-Regent is identical with that 
which has been described in the Bushwhacker and Della. Most of the 
workings run in dolomite below the fault, although the solid shale which 
forms the hanging wall is cut in many places. Between the solid shale 
‘and the dolomite there are generally about 40 or 50 feet of broken blue 
limestone and shale; but sometimes the dolomite and the solid shale come 
very close together, with practically no intervening breccia. The dip of 
the fault diminishes markedly upward, and increases with depth. This is 
shown by the Iowa incline, which, at the point near the bottom of the 
Towa shaft, is in solid shale, but soon runs into dolomite going down. . 
Where the incline runs into the Cowenhoven tunnel there are exposed 
some of the shaly and dolomitic beds of the Parting Quartzite, which strike 
with the tunnel and dip steeply west. At this point, however, the tunnel 
turns so as to run upward across the formations, reaching tlie solid shale 
again in a short distance. 
There is no continuous sheet of porphyry running parallel to the 
Silver fault in the Park-Regent, although there are occasional bowlders of 
it in the fault breccia. The dike which was noted in the Bushwhacker 
continues steadily across the Regent, and is last seen on the .first or 
uppermost level. 
Regent fault The Regent fault is marked in the tunnel by an offset to the 
west on the north side, the offset appearing to be about 30 feet. The main 
line of faulting is marked by a continuous open watercourse, traceable 
from the top to the bottom of the mine. From this main break south there 
is a series of parallel fractures, which are also often watercourses. The 
Regent fault appears to be nearly vertical in dip, and therefore to belong 
to a slightly different system from that of the Della fault. 
a 
