124 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
degrees to the west and a vertical downthrow of 1,300 feet on the north, 
and is very close to the actual separation. 
The distance by which formations would be separated by such a fault 
depends upon the angle of the dip, as observed, for the flatter the dip the 
greater will be the resulting distance. It therefore happens that in the 
eastern end of the area the formations are farther separated than they are 
a little farther west, for toward the west the dip becomes steeper and the 
apparent lateral displacement less. This may be noted in the distance 
between the contact of the Weber and the Maroon on the two sides of the 
fault. It is very likely, moreover, that toward the west the fault actually 
decreases in throw, the stress which in the more rigid rocks was relieved by 
actual displacement being partly taken up by interstitial movement in the 
loose sandstones. Thus it is probable that the fault loses most of its throw 
in traversing Red Mountain, for in the shales on the west side of Castle 
Creek fault there is no evidence of any large amount of displacement. (See 
Section B, Aspen district map, Atlas Sheet VII.) 
Of the east-west faults which appear north of Lenado, only one is shown 
on the map. This fault has an upthrow to the north of about 600 feet. 
(See Section G, Aspen district map.) In this way the dolomite on the south 
side is brought into contact with the granite on the north. The section just 
referred to shows throughout this area an uplifting of the beds along this 
faulted zone, which has somewhat of a correspondence with the similar 
uplift in the faulted area of Aspen Mountain and Tourtelotte Park, and 
is made conspicuous by the fact that in the Hunter Park district, which 
lies to the south, between Lenado and Aspen, there is no evidence of such 
disturbance. 
In point of age these east-west faults, of which the Lenado fault is 
typical, are evidently younger than the Silver fault, since they displace 
it in the same degree as they do the rock formations. Another fact which 
is significant as to their age is that in the case of the Lenado fault there is 
absolutely no evidence of mineralization throughout the most of its extent. 
As cut in the Bimetallic tunnel, for example, there is no trace whatever of 
its having been the channel of circulating mineral-bearing solutions. An 
apparent exception to this is in the Aspen Contact and Leadville mines, 
where much valuable ore has been taken out along the fault, and in these 
localities all the ore which has been shipped from Lenado has been found. 
