38 BOTANICAL FEATURES OF NORTH AMERICAN DESERTS. 
On various parts of the sloping walls of the basin are saline and alkaline 
springs. The flow in most of these springs is very slow, and low mounds 
are built up around the small pool of water, the soil becoming incrusted 
with the salts by evaporation. -Four plants make up most of the vegeta- 
tion, salt-grass (Distichlis spicata), Allenrolfea occidentalis, reed (Phrag- 
mites phragmites), and a rush (Juncus coopert). This last plant grows in 
enormous tufts and is of pronounced effectiveness as a soil-builder. In 
some of the moister springs, with soft, deep black mud, a three-angled 
spike-rush (Scirpus olneyt) was found, and in others the arrow-weed of 
the desert marshes. 
Between Rimlon and Palm Springs is an area in which the vegetation 
is subjected to strong sand-laden winds, a veritable sand-blast. The 
western faces of the wooden telegraph poles are deeply cut within 2 feet 
of the ground by the sharp, driving sand, and the railroad employees have 
found it necessary to pile stones about the bases of the poles in some spots 
to keep them from being actually cut off. The creosote-bushes have been 
molded into the most fantastic shapes. One of them standing in the lee 
of a small boulder ran its branches freely to the eastward, but the twigs 
that project upward and outward beyond the protection of the boulder 
were killed by the sand blast, so that the plant presented the appearance 
of a miniature box hedge about 1.5 feet high and wide and extending about 
4 feet from the rock. 
Clumps of Ephedra and plants of Yucca mohavensis, the cylindrical- 
stemmed Opuntia bigelovu and O. echinocarpa, and the flat-stemmed and 
spineless O. basilaris vary the desert vegetation until, in the vicinity of 
the station Cabezon, the creosote-bush ceases and the white sage (Ramona 
polystachya) and various other plants from the coastward side of the San 
Bernardino-San Jacinto Mountain barrier come out a little way through 
San Gorgonio Pass to meet the plants of the desert. | 
In the western part of the desert the clay forms the floor upon which 
in some places a thin layer of gravelly soil rests, while in other places the 
bare clay does not afford a foothold for seed-plants of any kind. Upon 
the eastern edge of the region lie the great sand-dunes which are known 
as ‘‘Los Algodones,”’ a name of Indian origin. These dunes are the more 
ordinary rounded hillocks by reason of the varying direction of the wind 
and are moving in a general northeasterly direction as a resultant. 
Such dunes actually support a very scant vegetation. 
A second series of lesser height, but scattered over a great area, are 
to be found in the great alluvial fan of the streamway of Carrizo Creek. 
Here the dunes are of the rarer crescentic form indicative of a steady wind 
in one direction with but little local deflection, the concave leeward face 
having a very steep slope and the convex windward slope being very 
gradual. Similar dunes on the Desert of Islay, in Peru, have recently : 
been described by Prof. Solon Bailey (The Sand Dunes of the Desert of 
