194 GUIDEBOOK OF THE WESTERN UNITED STATES. 
Although the river has been the principal agent in carving Ruby 
Canyon it has not done all the work, for the moisture in the atmos- 
phere and the sand blown by the winds are very active in wearing 
away the rocks. The results of the work of both of these agents may 
be seen at many places. The moisture in the atmosphere dissolves 
the cementing material that binds the grains of sand together, and 
the wind mechanically removes the loosened grains. These agencies 
acting together eat out cavities in the canyon wall, most of them 
small, though here and there one is excavated into an immense alcove 
having an arched roof. Wind-driven sand cuts the hard rock like a 
sand blast, and as the texture of the rocks differs from point to point 
the cutting has produced grotesque, fantastic forms. At some places 
the sand blast has cut the finest fretwork; at others it has simply 
rounded off projecting points of rock so that they stand out as great 
domes or circular minarets. Many such features cap the solid canyon 
wall, but they are so far above the track that the traveler can see them 
only as he looks ahead at some projecting spur or back at the disap- 
pearing view. At one place a group of columns on a salient point on 
the canyon wall resembles a procession of Egyptian figures, as show? 
in the ornamentation of their temples, and consequently these are 
known as “ The Egyptian Priests.” 
Beyond the place where the granite appears in the river bed the 
rocks dip gently downstream as far as milepost 479, where they are 
again elevated in a fold similar to that which has exposed the red 
sandstone just below Ruby. This fold is not so apparent from the 
train as that just mentioned, but by looking ahead from a point near 
milepost 479 the traveler may see it in the canyon wall on the right, 
and he may note traces on the projecting point on the opposite side. 
This fold raises the sandstone so high that the granite again appears 
in the river bed, rising at least 20 feet above ordinary water level and 
being visible from the train for about a mile. The river has had 
much greater difficulty in cutting the granite than in cutting the 
sandstone; the sandstone has been entirely removed, but the granite 
forms a very effectual barrier in which the stream has been able to 
cut only narrow channels, through which the water boils and tumbles, 
so that the rock is scoured and polished by the sand that the water 
carries over it. Pebbles accumulate in hollows of the rock and soon 
grind out deep holes where they are given a rotary motion by the cur- 
rent. Such holes, which are known as “ potholes,” are abundant 1m 
the granite in this canyon. 
In places the massive sandstone overhangs the railroad, as show? 
in Plate LX XX, A, and the beetling cliffs afford ideal sites for the 
Qn See age 
down, although in other places only a | at different localities different forma- 
part of them were removed. Hence | tions rest on the granite. 
