Rocky mountain Trip 
tremendous ; the walls rise with an unbroken slope to the summits 
of the quartzites. The carboniferous slopes form high ridges 
between the streams and are succeeded by the cretaceous lines of 
hog backs and the level plains and canon divided mesas. The shales 
between the bands of trachyte in the peak are changed to hard 
metallic like quartzitic slate with both over and under the trach¬ 
yte. The heads of the Manoos do not seem to cut deeper than the 
shales, the whole mountain and the neighboring spurs being made 
of alterations of shale and trachyte. In the head of Bear Creek, 
however, the red beds appear capped with a heavy bed of trachyte-. 
The red beds also appear beneath the trachyte in some of the east¬ 
ern summits. The trachyte extends considerably along the divide 
and caps a couple of points over toward the Wilson group. I 
doubt if ho. 1 occurs in the area between the forks of Bear River. 
The point occupied by Chittenden and myself last year on the ridge 
between Bear and Dolores Rios is Jurassic. Beneath is rea and 
then carboniferous. One of the buttes over toward Wilson is 
capped with trachyte. There is probably a dyke. A larg^ mass 
of trachyte on-the spur near where our mules were hitched does 
not belong to the bedded class but extends downward as if it be¬ 
longed to a subterranean macs. The cliffs are quite high where it 
is exposed. The heads of the valleys are full of slides of trach¬ 
yte. The great rounded beds of loose rocks look mobile as wax or 
dough. The whole of the lower slopes of the mountain consist of 
a series of irregular•steps caused by successive slides or aval¬ 
anche masses. Trees and brush cover the more gentle and less 
rocky slopes. It is curious that nearly the whole area between 
uhe Mancos and ix>st Canon is irregularly terraced by landslide 
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