250 
GEOLOGY. 
interior portions of the Desert. It is, indeed, a serious question whether a canal would not 
cause the overflow of a vast surface, and refill, to a certain extent, the dry valley of the Ancient 
Lake. This is possible, and would result, provided no change of level has taken place since the 
waters dried up. An overflow and submergence of the valley would produce great changes in 
the climate of that region, and permit navigation by small vessels from the Colorado to the 
base of the Bernardino Pass. 
In considering the adaptation of the surface of the Desert to agriculture, the peculiarities of 
the climate should he remembered. It is possible that they are such as to prevent the successful 
cultivation of crops, however rich and favorable the soil may he. The air is peculiarly hot and 
dry, and would have a burning and parching effect on vegetation. At certain seasons, and on 
parts of the Desert, the violence of the wind would greatly interfere with the growth of plants. 
The prevailing winds at Fort Yuma are from the north and northwest, hut southerly winds 
blow from June, to October.. The winds from the north are very dry and violent. They sweep 
down from the desert valleys and barren mountains, along the Colorado and the eastern side of 
the Great Basin, and before.reaching Fort Yuma are deprived of what little moisture they may 
have contained. They keep the air filled with clouds of dust, and heap up the sand-hills along 
the terrace. The violence of these winds is, however, not so great in the valley of the Desert, it 
being partially protected by the ranges on the northeast side; while at Fort Yuma the full force 
of the current down the valley of the river is experienced. The direction of the winds, and the 
temperatures for the different months of the year will be found in the following table, extracted 
irom the meteorological register kept at Fort Yuma. 1 
Thermo ii.eter. 
I__ 
Months. 
Monthly 
| mean. 
k 
Highest. 
Lowest. 
1852. 
o 
o 
o 
May_ 
81.85 
108 
52 
June_ 
91.66 
106 
68 
July .. 
93. 54 
108 
70 
August- 
92.74 
108 
70 
September... 
84. 56 
106 
60 
October__ 
73. 09 
98 
50 
November_ 
61. 83 
90 
38 
December___ 
56.51 
75 
32 
1853. 
January_ 
60.32 
80 
37 
February_ 
58.71 
78 
36 
March--- 
67. 56 
92 
40 
April-- 
74. 90 
98 
52 
May.. 
77 12 
99 
52 
June__ 
89. 04 
116 
61 
July. 
94. 93 
111 
76 
August. .. 
92.11 
110 
76 
September_ 
89. 08 
110 
69 
October_ 
79.30 
100 
50 
November........._ 
65.89 
86 
45 
Winds. 
1 
Rain. 
Inches. 
W. &SW. .. 
SW. & W. .. 
S. & SW_ 
.28 
S. & SE- 
.33 
s. &se.; 
1.45 
N. &NE_ 
N.& NW— 
.35 
N. & NW_ : 
. 04 
N. & NW_ 
NW. 
TOW. 
. 10 
NW. & W... 
NW. & W ... 
NW. & W.. 
S. & SE. 
.25 
S. & SW.. 
N.&NE_ 
.04 
N. & NW . 
NE. &NW-. 
.18 
4- This register has been carefully kept by Dr. Milhau, U. S. A., who kindly furnished me with the above abstract. 
