February 15, 1915 T35 
unable to force a way through them. Long ago Blake described 
their effect in sculpturing the granite rocks which lay in their 
path, and in the fifth volume of the Report of the Pacific Railroad 
Survey, page 82, he illustrates a rock from which the softer 
parts have been thus eaten out. A similar effect is seen on the 
windward sides of telegraph poles and section houses, where the 
wood is ridged by the cutting away of the softer layers. Along 
the railway derelict cans are discoated of tin and polished, and 
botths receive a frosted surfacing. 
From Whitewater to Palm Springs the joint selective action 
of water and wind has left the desert covered with boulders and 
gravel, from which most of the sand has been carried away, ex- 
cept where it lies heaped like snow drifts in the lee of some pro- 
jecting ledge of rock. It is at Pali Springs station that the 
real sand desert begins, and it extends to the margin of the van- 
ished Lake Cahuilla, near Indio, a distance of some twenty miles. 
The vegetation of these sands include no species of plants 
which are not found elsewhere in exposed parts of the desert. 
Its great interest is in the modification of form which has re- 
sulted from wind violence, and in the fact that most of the plants 
of the neighboring desert, although enduring an aridity and in- 
solation quite as severe as prevails on the Sands, find in the 
added factor of prevalent storms of wind an inhibition to their 
growth; a further condition of hardship in an environment 
already sufficiently unfavorable. The result is a flora of few 
species and of individuals remotely placed. This is emphasized 
at the upper end of the Sands, where the wind has its maximum 
force, while at the further end, where it is diminished, the num- 
ber of species is slightly larger, and the pupulation somewhat 
denser. But in no part of the desert, except in the occasional 
tracts of moist alkaline soil, can the adjective dense be applied 
to the vegetation in other than a comparative sense. 
That the vegetation growing in the throat of the pass above 
Palm Springs, where the force of the wind is at its maximuin, 
is more diversified, more abundant, and little modified in form, 
is due primarily to the character of the surface. This is much 
cut by the drainage channels, great and small, from the adja 
