RANGE PRESERVATION AND EROSION CONTROL. 5 
most violent period, with rocks containing as much as 30 cubic feet 
of material, the flood destroyed wagon roads, trails, and water 
ditches. 
Another typical example of flood and erosion occurred on July 30, 
1912, when a flow of torrential violence originated at the head of 
Becks Canyon. A rain, amounting to 0.55 of an inch, the greater 
part of which fell within an hour, started at 11 a. m., and at 11.45 
a. m. a flood was pouring out of a small side canyon which drains 
into Becks Canyon from an area of less than 1,500 acres, at an ele- 
vation of about 10,000 feet. This area is virtually treeless and is 
fan-shaped, the main drainage channel originating at the head of 
a steep canyon which drops into Becks Canyon at the rate of about 
1,000 feet in less than a mile. The soil is of a clay-loam type, and, 
considering the area as a whole, is of fair depth, there being but 
little outcrop. The slopes are moderately gentle, and because of 
this fact the area had not been included in the adjacent one which 
was protected from grazing until late in the season. An examination 
after the flood showed that the soil had been very densely packed 
by grazing previous to the storm. The whole of this small water- 
shed was well marked with gullies. The flood was not observed 
until it reached the mouth of the side canyon. Here it presented a 
front approximately 8 feet wide and 1| feet high. The water was 
so infiltrated with sediment that it did not run but rolled over and 
over, picking up small rock and gravel. The flow increased to a 
front of from 10 to 25 feet wide and from 6 to 8 feet high. The 
velocity and force of the rolling mass down the steep slope were 
appalling. The main flow lasted approximately one hour, varying 
in volume .as had the rain 30 minutes previous. Owing to the enor- 
mous deposits of debris, the course at the mouth of the channel 
changed three times. As the stream changed its course from one 
side to another enormous quantities of material were deposited only 
to be carried away later. At one time approximately 5,000 cubic 
feet of the bank was torn out in a few minutes as the old bed filled 
up with material from above. All these tons of soil, vegetable 
matter, and other material were carried down by the rushing water 
in less than two hours after the rain began to fall. 
In addition to the direct loss of personal property, damage to the 
range itself in the way of decreased forage production and soil de- 
pletion has a most vital effect on a community. Such loss is seldom 
fully appreciated until the stockmen must, of necessity, limit the 
number of animals grazed on the lands. Following the action of 
a few destructive floods, the productivity of the grazing lands may 
be 30 decreased that only the more inferior drought-resistant plants 
will thrive. Where the farm lands, upon which supplemental win- 
ter feed is grown, are remote from shipping points, as is true of much 
