LENADO SPECIAL MAP. 125 
It is the opinion of those who have worked these mines, however—and their 
opinion has been agreed to by the writer, after careful examination—that 
the broken and bunchy condition of the ore indicates that it was not formed 
in place, but has been dragged up along the fault from some other locality. 
The usually barren condition of the fault goes to show that it originated 
later than the ore deposition, and the conclusions which have been arrived 
at in regard to the ore in the Aspen Contact and Leadville mines point in 
the same direction. 
Another slight point in the determination of the age of this fault is the 
topography. Where the fault cuts across the top of the cliff on the south 
side of the canyon, it forms a groove instead of a scarp. This is evidence 
that there has been no movement of importance since the Glacial period. 
The age of the fault is therefore determined as postmineral and pre-Glacial. 
DESCRIPTION OF SECTIONS. 
Section A——On the eastern side of this section, which, like all other east- 
west sections, looks toward the north, the slight anticlinal structure, as 
exhibited in the cliffs above Lenado, is shown. The various formations 
represented in this section are actually visible, for in traversing this line 
one passes from Cambrian quartzite and the Silurian dolomite into the 
Parting Quartzite, which outcrops on the side of the hill and in the bottom 
of a little gulch, as indicated; then across a slight thickness of Leadville 
dolomite to the Silver fault, which is encountered at the bottom of the 
gulch in which the Tilly shaft is located. Farther on are the westerly 
dipping Weber beds, and overlying these the whole thickness of Maroon 
sandstones, with thin-bedded limestones and shales, while at the extreme 
western end of the section comes the assumed contact between the Maroon 
and the Triassic beds. In this section the thickness of Leadville dolomite 
between the Parting Quartzite and the Silver fault is very slight, probably 
about 100 feet. This may be due to the faulting, as previously explained, 
or possibly to the erosion which took place previous to the deposition of 
the Weber rocks. 
Section B—'This section is taken across the Lenado fault. Its eastern 
end is in granite, and it runs west into the steeply dipping Cambrian 
quartzite. After passing across the upturned edge of the quartzite to the 
lowest beds of the Silurian dolomite, the Lenado fault is encountered, 
