LENADO SPECIAL MAP. 119 
Farther west the dip steepens gradually, until, at the western end of the 
section, it averages perhaps 45 or 50 degrees. 
Along the valley of Woody Creek the rock exposures are almost con- 
tinuous, so that a complete section is obtained. After passing westward 
through the canyon above described, there are successively encountered the 
Silurian dolomite, the Parting Quartzite, the Carboniferous dolomite, and 
the overlying Weber shales. Above these come the Maroon beds, with 
their basal gray limestone. These Maroon beds run continuously in the 
bottom of Woody Creek as far as the limit of the area mapped, but at some 
little distance west the line of division between the Triassic and the Car- 
boniferous has been placed, and the strike of this contact just carries it 
across the top of the hill in the extreme northwestern end of the area. 
The successive formations over which the creek passes in its westerly 
course give rise each to different variations in the shape of the valley. 
Above the Archean gateway which has been described the valley broadens 
out, being flanked on either side by steep granite hills which have been 
worn down from their original shape by the action of glaciers. The sharp- 
ness of the canyon across the anticlinal fold is apparently due not so much 
to the nature of the rocks. as to the presence of the fold. The center of 
the dome, which has a steep dip to the west and a gentle dip to the north, 
the south, and the east, has been eroded with comparative ease, while the 
rocks on its sides have been more resistant. Just west of this canyon 
erosion has gone on with much greater rapidity, so that the widening out 
of the valley is very striking. The side gulches which run into the main 
creek now have a considerable length and a comparatively low gradient. 
This is seen in Pl. XIII, from a photograph taken from Woody Creek look- 
ing up Silver Creek, which is one of the side gulches referred to. This 
gulch has been eroded in the Weber shales, about midway between the 
contact with the Maroon on the west and the contact of the Leadville dolo- 
mite on the east. The Maroon beds come in at the extreme left of the 
picture. After passing through the Weber formation and entering the red 
sandstones of the Maroon, followed by similar but probably Triassic rocks, 
the valley of Woody Creek assumes again a new form, which is continuous 
throughout a large part of its course, until it passes beyond the sandstones. 
This part of the valley is in general v-shaped, the hills on both sides hay- 
ing a steep but uniform slope, and the side gulches being short, with steep 
