152 Fossil Shells from the Colorado Desert. [ March, 
The remarkable season of 1861-2, when the great California 
basin was flooded and the larger portion of the valleys included 
between the coast range and the Sierra Nevada was for weeks 
covered with water, and connected at times, so as to form an ex- 
tensive lake, this winter also embraced within the area of its se- 
verity the more interior basin east of the Sierra. While, doubt- 
less, the volume of the Colorado was greatly increased through 
the contributions of its tributaries in its upper portion, it also 
must have received an extraordinary supply from the drainage 
slopes farther to the south. The record of unusually high water 
or floods in the Colorado includes the winter of 1861-2 as well 
as several seasons not remarkably wet in California. In the 
preliminary report of Lieut. Bergland? on the feasibility of 
diverting the Colorado for the purposes of irrigation, he esti- 
mates the area of depression below the sea level within the lim- 
its of California at approximately “ 1,600 square miles,” yet dur- 
ing the severe winter especially referred to, an area estimated to be 
sixty miles long by thirty miles wide was covered with water? A 
portion of this was without question the surplus surface drainage 
from the adjacent country as well as the overflow of the Colorado, 
though the New River channel, and the main stream may have 
poured a portion of its water, in times gone by, over the desert, 
through other channels. 
The sedimentary deposit under consideration and the lake whose 
waters once held it in suspension, and covered the present desert, 
may be accounted for in this way, and its permanence, over the 
area covered and the depth of water on which its area depended, 
only required a more constant volume in the Colorado, a less 
rapid rate of evaporation, even if the topographical features are 
the same now as then. 
With the data accumulated by various intelligent and trust- 
worthy observers, and accessible to all who are disposed to inves- 
tigate, we are justified in the conclusion that without spasmodic 
1 Wheeler’s Report, 1876, p. 109. 
2 Mr, Jaeger, owner of the Ferry at Fort Yuma, and a resident of the place since 
its establishment as a military post, says, “ Heavy floods in 1840, 1852, 1859, 1862 
and 1867. Tasted the water flowing in channel at New River station in 1862, and 
found it fresh water. A Mr. Jones (now dead) told me that he came along the west 
side of the great basin in 1862, on his way from San Bernardino to New River, and saw 
in the basin a great lake, some sixty miles long by sired wide. This came from the 
overfiow i in 1862.” Id. 118. 
