ASPEN SPECIAL MAP. 719 
Creek Valley, some distance to the east. The sides of the mountain, 
however, are in large part bare and afford practically continuous outcrops. 
Near the base of the mountain there are seen strongly marked, broad, 
successive terraces, which are continuous from this point down the valley 
for several miles. These terraces are carved out of the bed rock, but are 
covered and often disfigured by morainal material; it appears probable 
that they mark the shore lines of a lake which existed in the Roaring 
Fork Valley just where the town of Aspen is located. The plate also 
shows a typical portion of the town itself, with the Hunter Creek Valley 
in the right background. 
DESCRIPTION OF SECTIONS. 
Section A—Section A (Atlas Sheet X) traverses Smuggler Mountain, 
passing through the mouth of the Johnson tunnel, and runs along the top 
of the uppermost and most strongly marked terrace at the base of Red 
Mountain. This section presents no complications in the way of folding, 
since all the beds have a uniform steep northwesterly dip. This dip is 
apparently greatest close to the granite on the east side of the section, and 
least in the Maroon beds on the west side. The Silver fault is seen in this 
section separating the dolomite of the Leadville formation from the Weber 
shales. There is also a thin sheet of porphyry lying at a variable but 
always short distance above the fault, which represents very nearly the 
northern termination of the main porphyry sheet. This sheet, although 
represented in the section as continuous, is actually crushed, broken, and 
intermittent, showing that it has been profoundly influenced by the effects 
of the fault. There is in this section none of the blue Leadville lime- 
stone, but the dolomite always lies immediately below the fault. 
The Della fault is actually developed in that part of the section west 
of the Johnson tunnel, as is here represented, having a perpendicular sepa- 
ration to the west, on the north or under side, of about 200 feet. This fault 
displaces the Silver fault. The uplifted portion of the Della fault which 
appears on the east side of the Johnson tunnel is not shown underground, 
since there are no workings in this vicinity, but it is put in on theoretical 
grounds. The nearly vertical fault which displaces the Della fault is the 
Clark. This, also, is not actually proved, as shown in the section, but, 
judging from its effect in the workings of the Mollie and the Smuggler, it 
