42 
showing that the portion of the desert 
where they are now found was once 
eovered by brackish water.’’-—J. S&S. 
Newberry. 
Dr. J. G. Cooper reports (in bulletin 
4, California state mining bureau, pages 
58 and 59) the discovery by H. W. 
Fairbanks, near Carrizo creek of ‘‘fos- 
sile coral-islands, the coral forming ex- 
tensive beds about the summits of 
short isolated ridges detached from the 
mountains of the western rim, and con- 
sisting at their bases of granitic or 
metamorphic rocks. The ridges appear 
to have been islands when the desert 
formed part of the Gulf of California, 
or of the Pacific ocean, and were at the 
right depth beneath the surface for 
coral growth on their summits for a 
long period. With the coral occurred 
several fossil shells of forms quite un- 
like those of the late tertiary of Car- 
rizo creek beds, and apparently unlike 
those now inhabiting the Gulf of Cali- 
fornia.” 
Fragments of fossiliferous rock of 
the Carboniferous age have been found 
in the Carrizo creek region by various 
collectors, but none in place have yet 
been reported. 
The Indians, according to Dr. Stephen 
Bowers, still preserve the memory of 
catching fish aiong the eastern base of 
the San Jacinto mountains, where the 
Cahuilla Indians pointed out to him 
the artificial pools, or ‘‘stone fish 
traps,’’ where their ancestors easily se- 
cured the fish on the receding of the 
tides of the ancient sea. This would 
seem to indicate that the change from 
an arm of the gulf is comparatively 
recent, and a study of the fossils seems 
to confirm this view. An old Indian 
in the Cuyamaca mountains pointed 
out to miners a few years ago points 
in the hills to the eastward where his 
great grandfather used to catch fish 
from the sea. 
The cause of the separation of this 
region from the gulf can be readily un- 
derstood in the present encroachment 
of the land that is forming from the 
sediment and debris of the Colorado 
river, where it empties into the gulf. 
With the formation of a barrier separ- 
ating thebasin from the gulf, the im- 
prisoned waters were at once subject- 
43 
ed to rapid evaporation. 
The presence of fresh water shells 
in a semi-fossil condition, of a brack- 
ish water mollusk, and of marine shells 
of species now found living at San 
Diego, on the Pacific side, would seem 
to indicate that thegreat changes which 
have unquestionably taken place in 
this remarkable region were the re- 
sult of natural phenomena of gradual, 
yet rapid, occurrence. After its iso- 
lation from the sea, with rapid evapor- 
ation, few years were requisite to 
transform this basin from an arm of 
the sea to a barren waste, the salt of 
the sea water forming the salt mines 
at Salton. 
The Colorado river doubtless hurried 
past as it does today to the gulf, until 
breaking down.-the barrier it had itself 
erected. With alternate periods of 
evaporation and influx of fresh wa- 
ter, the great basin changed first to 
a brackish lagoon, and finally to a vast 
fresh water lake. 
The water of the Colorado river at 
Yuma is known to carry at high wa- 
ter not less than ten per centum of 
solid matter. The deposit of this sedi- 
ment in the great basin doubtless rap- 
idly formed the deep and fertile lands 
which are now being harnessed into 
service at Indio and Imperial, and 
being converted at the latter place, by 
the utilizing under control of the wa- 
ter from the Colorado river, into fields 
of agricultural promise. 
Dr. Robert Edward Carter Stearns, in 
a paper read before the California 
academy of sciences, entitled ‘““Remarks 
on fossil shells from the Colorado 
Desert’? (published in the American 
Naturalist, 13:141-154, March, 1879), dis- 
cussed the occurrence of fresh water 
shells found in a well at Walter’s sta- 
tion at a depth of fifty feet. The sur- 
face of the desert where this well was 
sunk is 195.54 feet below sea level. Dr. 
Stearns remarks: 
“Shall we indulge in a guess as to 
the depth of the water when these 
shells were alive? Shall we add the 
depth of the well to the elevation of 
bench marks, the ancient levels which 
form terrace lines in some places along 
the distant hills, once a part of the 
shores of an ancient lake, the walls of 
