<2 SRR rege 
DENVER & RIO GRANDE WESTERN ROUTE. 209 
_ to the absence of streams and to the presence of a greater number of 
beds of sandstone in the west than in the east, as well as to the more 
massive character of these beds and to,the greater dips which pre- 
vail in this part of the plateau, for all these characteristics would 
give a very different result in the forms produced by erosion. The 
Book Cliffs west of Green River are characterized by many bands 
of sandstone, which may be followed by the eye for long distances 
and which produce slight benches on the slope. <A profile of a part 
of the front of the Beckwith Plateau is shown in figure 55. 
A geologist accustomed to interpret the meaning of land forms 
sees almost everywhere in these shale areas fragments of older sur- 
faces of the land, preserved in terraces and benches. Some of these 
remnants of an older surface were pointed out west of Grand Junc- 
tion and again near Thompson. West of Green River they grow 
more and more prominent as the traveler approaches the head of the 
stream. They stand at 
different heights above 
the present general sur- 
face, but commonly 
some particular ter- 
race—one that ranges 
in height from 50 to RoC — 
200 feet above the pres- Narieow latinte ———— 
ent surface—is more ——s = 
prominent than the — ————— 
rest. The old surface ———SSS SS 
in this region was er or ae cere 
probably more nearl 
smooth and regular than the surface of to-day, and its slope 
was doubtless not so great as that of the present surface. After 
this old:surface had been well developed, the lower country, though 
it showed considerable differences in elevation between the higher 
and the lower parts of its slopes, must have formed one general 
plain. Then came a change, either an uplift of the land or an in- 
crease in the rainfall. At any rate, the streams were able to cut 
deep trenches in this old surface, and their work has been continued 
So long that it has left, here and there, only remnants of the once 
continuous surface, and these remnants are the terraces and benches 
that we see to-day. Terraces are very prominent in places west of 
Woodside, and the traveler may be interested in studying them, not 
as terraces but as remnants of that old surface. Indeed, he may be 
able in imagination to reconstruct from them the old surface as it 
caine before the streams had cut into it and carved the valleys of 
y- | ) 
Mesaverde formation 
Ficurn 55.—Profile of front of Beckwith Plateau, 
