DAVIS: THE PLATEAU PROVINCE OF UTAH AND ARIZONA. 11 
where the meadow broadened as the creek divided and spread over the plain. 
It was almost impossible to ride a horse up the canyon on account of the mud- 
holes, quick sands and brushy thickets. The water in the creek was so low — 
that from about May 20 to August 1, the stream would reach the village near 
the mouth of the canyon only from about day-break to 11 a.m. 
In 1874, the meadow in the canyon was thrown open to stock, by which the 
vegetation was gradually destroyed. The creek was thus concentrated in fewer 
channels and its flow was increased more than half. Between 1874 and 1883, 
the canyon floor was fenced up, and the small fields were sowed with red-top 
and timothy ; at the same time, the creek channel was better defined. A road 
was then constructed through the canyon. 
The first great flood came on July 29, 1883. It swept away all of the farms 
and meadow lands in the canyon, as well ag the field crops just south of the 
village, and scoured out a broad channel beneath the former valley floor. In pass- 
ing Kanab, the flood was pronounced “ as wide as the Missouri river,” a rushing 
stream of liquid mud, bearing cedars, willows, and great lumps of earth. Dur- 
ing the winters of 1884 and 18835, the plateaus of the Kanab headwaters received 
an unusually heavy snowfall ; it lay in places ten feet deep on the level and 
lasted until April. Then as the sun thawed the snowbanks, floods occurred 
daily for three or four weeks and continued the deepening of the new channel 
through the canyon. Asa result of three years’ washing, the stream bed was 
cut down about sixty feet beneath its former level, with a breadth of some 
seventy feet, for a distance of fifteen miles.” 
The meaning of this remarkable change seems to be that canyons in 
an arid region are aggraded during periods of low water, and degraded 
at times of exceptional floods. It may be inferred that the duration of 
the aggrading periods is short in young canyons of relatively steep slope, 
and that only as the graded condition is approached and reached do 
longer and longer periods of aggradation come to alternate with spasms 
of degradation. If this inference is correct, it may be further inferred 
that the streams of arid climates differ in this respect chiefly in degree 
rather than in kind from streams in regions of more plentiful and regu- 
lar rainfall: for the latter are known to clog their channels with bars 
and shoals at times of low water, and to scour them out during floods ; 
but in the latter case the form of the channel after the flood closely re- 
sembles the condition before the flood, while it is greatly altered in the 
former case. 
The scouring of Kanab canyon was checked at two or three points 
where the flooded stream happened to cut down its channel so near one 
side of the valley floor as to become superposed upon a previously buried 
rocky spur of the canyon wall. In such cases only a narrow and rela- 
tively shallow notch was cut in the rock, down-stream from which there 
