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 be remembered. It is possible that they are such as to prevent the successful 
cultivation of crops, however rich and favorable the soil may be. The air is peculiarly hot and 
dry, and would have a burning and parching effect on vegetation. At certain seasons, an’ 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, but 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 
theterrace. The violence of these winds is, however, not so greatin 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 
Írom the meteorological register kept at Fort Yuma.! 
| Thermometer. 
Months. Winds. Rain. 
Monthly |Highest. | Lowest. 
mean. 3 
1852. e bi ó Inches. 
May 81. 85 108 ED WS Sy. LLL... 
June - 91. 66 106 68 | SW. &W. ..|--.--. 
July 93. 54 108 70. | S. &SW...- 28 
ROE I ES 92. 74 108 ru. 33 
Bepteinber..-- 5. 84. 56 106 60 | S. & SE..... 1. 45 
OO 73. 09 98 50 | N. &NE " 
November 61. 83 90 328. N ENW 35 
DESDE aa 56.51 75 32 | N.£ NW... 04 
1853. . 
JABUNFY oer nr anes 60. 32 80 57 |N:&NW...]....-- 
February 58. 71 78 36. de N Wei an AS 
March 67. 56 92 400: WWW... 10 
April 74. 90 98 52, | NW. SW... isn 
May 77 12 99 52 | NW. & W...|------ 
June - 89. 04 116 61 | NW. & W...|------ 
July 94. 93 111 76 | S. &SE...-. 25 
dKuguit LU Ala. 92. 11 110 76: | 8. & BW....|--.--- 
September...........| 89. 08 110 69 | N.& NE..-- 04 
A ud oo nn nnd 79.30 100 50 | N. &NW...|------ 
November...... —— | 65. 89 86 45 | NE. & NW..| .18 
1 This register has been carefully kept by Dr. Milhau, U.S. A., who kindly furnished me with the above abstract. 
