The Julesburg grit-advocate. (Julesburg, Colo.) 1907-1972, 1910-07-07


ing power inersasss q times with
saD Ssubling ef tAs velocity: 70 that
Il you Increase Tia velocity thresfold
yos have i.ersaasA ths Transporting
power q the wetse 10 times and II
yos snaArupIs II 20 have increased
- weight Of ths pebble which II
vosld move 4yoSs times. This at Arst
tAosghk seems incredible. but It b
asvsethslsss tue. and prepares - 70
appreciate the astonishing results that
arc produced BY SsaniAg watsr.
Water moving three test In . SEC
cad. o. . mile IN six hours. will carry
along with Il particles Of nne clay
and keep them n suspension. Water
moving st twies that velocity viii lift
md carry aioag With It dns sand:
while velocity four times ~ great
will sweep aioag ane gravel and water
moving at the rate Of two miles an
hour will carry along stones ~ big ~
. hens sgs. There ID hardly any limit
to the size Of . pebble that would b
rolled along By . current Of six o.
eight miles IN hour. blocks - big -
houses being sometimes set IN motion
and transported for considerable dis
tances.
In various ways one can obtain pos.
tive evidence Of this power Of water
transportation. II. for instance. he 1t.
tsmpts to wade aeross the Platte
river In Nebraska, which 10 over.
loaded with sand and has . gradient
Of eeven or eight feet to the mile. and
hence . very rapid current. he will
hnd his bare legs stung by the par
ticles Of sand and nne gravel that arc
driven against them. Or II after .
storm one pauses to listen he will
hear what sounds like distant can
nopading. produced BY the knocking
Of e stones together ~ they are
rolled along upon the bottom Of the
stream.
The erosive power Of 4 stream now-
ing over . rocky bed IL determined by
its ability to shove along sand and
pebbles and gravel over its bottom. It
Is these PARTICLES Of solid matter that
accomplish the erosion, acting AZ .
rasp. or sandpaper. or more properly
q sand blast, to remove the solid rock
beneath and deepen the channel OF q
stream. In order to do this. however.
there has to be proper adjustment be-
tween the supply Of loose solid matter
to be transported and the volume and
velocity Of the water. II there Is more
sand and gravel than the current can
handle. this will accumulate upon the
bottom and ali up rather than deepen
the bed. II there is too little material
the stream will flow over the rocks
without effecting much erosion. while
II there Is just the right amount Of
solid matter to be showed along It will
deepen the channel with great rapid.
ity.
There are many striking examples
Of the work which has been accom-
plished by rivers In deepening and
widening their channels. We look
upon the rise of mountain chains as
being most majestic illustrations Of
the power Of natural forces. but the
fact Is equally impressive that in many
cases rivers which run across the line
Of psI,lntain elevation are able to wear
dow = their channels a. fast Is the
mountains rise and thus maintain
their ancient onward course. The
Hudson river has thus sawed down b
channel through the solid rocks which
in ancient geologic times arose across
its course at West Point and below.
all that picturesque valley Of the Hud.
son being 4 valley Of erosion. The
Delaware river has worn IN even
more striking gorge through the Blue
Ridge at the Delaware Water Gap
where It cuts directly across the very
hard strata Of Medina sandstone con,
shutting Blue Ridge. forming perpen.
dicular walls on either side 1000 feet
In height. Similar gorges are found
in the Susquehanna and Potomac and
many other rivers along the Appa.
lachian chain Just above where they
emerge upon the surrounding lowland.
We often speak Of such rivers as
bursting" through their barrier. But
there was no bursting In the opera.
ton. These gorges were cut by the
slow process which we have described,
the rivers lowering their channels
gradually as the mountains slowly rose
across them.
Among the most striking examples
Of rivers which have by erosion kept
pace with the elevation Of mountains
across their course is that Of the Co
lumbia river, in Oregon, where for a
long distance 1t occupies trough
running directly through the mountain
chain thousands Of feet in depth. An
other very striking instance is that
to be seen In the Amur river where
it lssse s the Bureya mountains in
easNn Siberia. For nearly 100 miles