168 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
Mountain to near Castle Butte at the south side of the park. At this latter 
point the northerly pitch of the beds carries the upper formations, such 
as the shale, and finally the blue Leadville limestone, above the surface, 
and with them the Silver and the Contact faults. South of this point the 
country has been comparatively barren, and is not likely ever to be 
very productive, with certain exceptions, such as in localities along the 
Castle Creek or its dependent faults, where there appears to have been 
ereat mineralization. 
Bay State shatt—The Bay State shaft lies close to the northern border of 
the district shown on the Tourtelotte Park ming map. The workings are 
in the blue Leadville limestone and in the dolomite of the same formation, 
exposing the Contact fault. This fault carries some ore, but no very 
important body. There has been some cross faulting in the mine, by which 
the Contact fault has been shifted about. 
Ruby min.—The Ruby mine is near the Bay State, and shows practically 
the same conditions. The shaft, which is 385 feet deep, starts in shale, 
crosses the Silver fault, and proceeds downward through the blue limestone 
across the Contact fault into the dolomite. There has been a great deal of 
faulting in this mine, which has shifted the formations considerably, but 
the faults do not seem to be very heavy or persistent. East of the shaft 
the general effect seems to have been to thrust the formations down slightly 
on the east side. There are two sets of fractures in the mine corresponding 
with the two sets of slight faults, one of which runs north and south, and 
the other east and west; and, so far as can be judged from the somewhat 
meager evidence, the east-west faults antedate the north-south ones. Both 
of these fracture systems seem to have influenced the deposition of ore, and 
some valuable bodies have been discovered along them. Most of the ore, 
however, occurs in the vicinity of the Contact fault. 
Little Percy mine—The Little Percy mine is situated a short distance south 
of the Ruby, and shows very nearly the same conditions. The chief work- 
ings consist of an incline which starts on the hillside at the outeropping of 
the Contact fault on the east limb of the Aspen Mountain syncline. This 
incline runs in a northwesterly direction for over 1,300 feet, having a vary- 
ing pitch. For most of this distance it is in the Leadville dolomite, or in the 
Contact fault, which is marked by a brecciated zone containing large frag- 
ments of shale and porphyry. From this incline there run out at mtervals 
