26 UNITED STATES AND MEXICAN BOUNDARY. 
towards the sources of the streams or from local springs, were often of great length and magni- 
tude. The one belonging to the San Diego mission, for instance, is a continuous wall of 
masonry for the distance of nearly three miles. The upper portion of each valley was generally 
occupied by a branch dependency of the main mission, thus securing the entire control of the 
agricultural resources of the valley. 
In regard to the eastern slope of the mountain but little additional need be said. In the 
immediate vicinity of the summit ridge arable land is found, but the more precipitous slope 
renders this too limited in extent to claim much attention. Desert valleys and pent up caiions 
succeed between this and the great plain. As far as all agricultural purposes are concerned 
this is truly a desert, though it is not, as is generally supposed, a mere waste of shifting sands, 
and destitute of every kind of vegetation. 
We have already noticed that several shrubs are peculiar to this tract, which, if they serve 
no other purpose, at least afford relief to the eye. | 
The borders of ‘‘ New River’’ being subject to frequent if not regular overflow, would seem 
to present some opportunities for the limited cultivation of maize, beans, pumpkins, and melons, 
such as is practiced by the Indians on the Colorado, and the existence of “ gramma grass" on 
the higher adjoining ground would seem to indicate that quickly maturing cereals might be 
raised here. | 
The supply of water might, moreover, be rendered more constant and equable by the con- 
struction of artificial reservoirs and ditches. Still we must admit that any system of cultivation 
must be very precarious in a location where its success depends upon such variable causes. 
The remarks respecting “New River” apply in a great measure to the Colorado. Неге the 
` cultivation is, of necessity, confined to those portions of the valley that are subject to overflow and 
the consequent deposition of fertilizing sediment. The higher adjoining lands, being without 
the reach of these influences, are, from their extreme aridity and the light porous nature of 
their soil, quite unfit for any cultivation. 
All the Indian settlements upon the Colorado with which we are acquainted are located with 
reference to an overflowed portion of the river margin. Near the junction of the Gila with this 
river one Indian village occupies an old river bed, which, when the river is high, is completely 
covered by the stream. Another settlement is situated upon a low alluvial delta lying between 
the two rivers, and a third is built in a slough. These are also flooded at high water. The 
articles cultivated by these Indians are principally maize; beans, and pumpkins. No doubt 
that cotton, sugar, and many of the sub-tropical fruits would succeed here, but our present 
knowledge respecting the extent of arable soil, of the vicissitudes of the climate, and of the 
character of the different seasons, is too vague to warrant any but the merest conjecture in regard 
to its future agricultural importance. 
