Abilene weekly reflector. [volume] (Abilene, Kan.) 1888-1935, 1909-03-25

Il
a small amount of water in 1t, and
that will move at slow pace, and
will have but little carrying capaci-
ty. Its work in deepening the
channel will consist principally In
the dissolving power of the water.
But when the heavy rains come and
ten, twenty and hundred times the
amount of water is poured into the
channel the velocity of the moving
water is greatly increased, and the
carrying power correspondingly in
creased according to the ratio above
named. The energy Of this moving
water will be devoted principally to
cutting its channel deeper, until the
water has all the load 1t can carry.
In order to Deepen its channel more,
therefore, 1t must be given greater
velocity, or in some way 1t must get
rid of some of its load.
Suppose now that at some place
along the channel the velocity
should be checked, never so little
possibly. With a decrease in veloc-
ity the carrying power will be de-
creased sixty-four times as much. II
the water was loaded to its limit q
part of that load will be deposited
the very instant a perceptible check
ing of the velocity is brought about.
At that instant therefore, the water
ceases to cut its channel deeper and
the reverse process begun, that OF
filling up the channel. Usually the
decrease in velocity is at or near the
mouth of the stream SO that the fill
ing up process begins at the mouth.
1t is common, therefore, to find a
stream which is still cutting its
channel deeper in its upper parts
and the same stream filling up its
channel in the lower part Of its
course.
II now, we have a stream that
rises In mountainous district and
flows across a plain area, and ulti-
mately enters the ocean, we have
such variety of surface inclina-
lions that complications are set up.
When the terrific rains come in the
mountains the streams with high
declivty assume the proportions of
mountain torrents and the carrying
power of the water becomes so enor-
mously great that mud and silt and
sand, gravel and boulders altogether
are hurled downward as though they
were mere toys. Few can appreciate
the limit of such power. have seen
boulders egg-shaped in proportion,
more than twenty feet in diameter,
weighing doubtless more than a hun
dred tons, which have been carried
along by these mountain torrents;
and, as they went humping the bot
toms and the sides of the channel
they produced wonderful execution.
The same stream of water, however,
can not have this high velocity for
ever, and as the plains region is
reached the angle of declivity is re-
duced, the velocity correspondingly
is retarded, the carrying power is
much more reduced and the unload
ing process is necessary. The first
objects to be unlOaded, Of course,
will be the largest ones. The force
Of the water against a boulder, or
gravel, or grain of sand is proper
.ional to One-half the surface Of the
object, which, in turn, is proportional
o the square Of the diameter, while
he weight is proportional to the vol
lme, and that in turn proportional
@ the cube ofhe diameter. Therefore
he largest objects will be dropped
irst.
Visit a mountain stream wherever
,ou may and you will and the bOuld-
RS accommodating where the first
heck in the velocity of the current
vas brought about. If the decrease
n velocity is sufficiently great,
and and mud will be intermingled !
With the boulders, but II the de- &
rease was limited, that we find the .
,oulders washed clean, the finer &
articles having been carried farther '
long. l need only revert to such /
treams as the Rio Grande rising in ?
be mountains above Albuquerque, s
be Arkansas rising in the vicinity b
I Cripple Greek, the Potomac ris- v
liz on the summit of the Appala- v
hans, or any one Of the many o
Their streams known to all. Where p
he angle in the surface is greatest s
lere the most unloading occurs. o
This unloading sometimes reaches p
normous proportions, and the river o
uiids up its channel until in ex- ii
-eme case it is hundreds Of feet p
bove the plains on either side. OF II
purse such conditions cannot exist p
ing and sooner or later the water c.
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