56 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
the bed of a lake subsequent to the greatest activity of the Glacial period, 
and that on the bottom of the lake the morainal material was sorted and 
leveled so as to form the flat plain which exists at present. In the back- 
ground, looking up Roaring Fork Valley, are seen the peaks of the Sawatch. 
On the left hand, or northerly side of the picture, most of the hillside is 
granite, with the sedimentary formations of Smuggler Mountain coming in 
above; these sedimentary formations are continuous with those in the 
hollow of Aspen Mountain. In the extreme left is the east side of Red 
Mountain, which is separated from Smuggler by the valley of Hunter Creek. 
The name Smuggler Mountain is applied especially to the small, flat-topped 
hill with heavy side gulches which lies to the west and below the mountain, 
whose outline stands out against the sky. The top of this hill is not far 
above the level of Hunter Creek Valley, and is heavily covered with glacial 
drift. The main mountain back of Smuggler Mountain proper is of granite, 
and this rock extends from here to the gateway in the Roaring Fork Valley. 
In the left foreground, on the spur of Red Mountain, come in the red Maroon 
beds. 
ASPEN MOUNTAIN. 
FOLDING. 
In the northeast part of the area shown on the Aspen special map 
(Atlas Sheet IX) the only feature in the plication of the beds is the usual 
simple westerly dip, which extends from the granite through the Cambrian, 
Silurian, Devonian and various Carboniferous formations. In the extreme 
northwestern corner of the area the steep westerly dip grows shallower, 
showing the approaching synclinal structure which is exhibited near Red 
Butte, where the beds abut against the Castle Creek fault. 
In the area shown on the southern part of the map, however, on Aspen 
Mountain, there is a sudden and remarkable change in the position of the 
beds. Here is developed a new folding in two directions, one parallel to 
the strike and another one at right angles to it. The longitudinal section 
(see Section G, Aspen district map, Atlas Sheet VII) shows a sudden 
bending-up of the beds along the strike at this point. This doming-up, as 
measured in the section referred to, amounts to 5,000 feet or more in the 
distance between the Roaring Fork and the top of Aspen Mountain. This 
amount is partly due to intervening faults, which likewise tend to raise the 
beds toward the south. These faults, however, are intimately connected 
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