The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1856-1888, 1882-11-18
CAPTAIN BUTTONS LECTURE ON
RIVERS"

Last evening the New Music Hall was
well-hlled by an appreciative audience TO
listen to Captain Duiton, of the United
States Geological Survey Department, lee
ture on Rivers" His Majesty, accompa-
MED by His Excellency Walter Murray
Gibson, Minister of Foreign Affairs were
present. We are indebted to the lecturer
for the following synopsis of his subject -
The rivers of the Atlantic States, like the
Hudson, Delaware, Susquehanna and Potamac
have their sources far inland at elevations of
only a few hundred feet. In order to reach the
sea, they pass through ridge after ridge of the
Appalachians, in deep, narrow gorges. How
were these gorges formed, which are SO con-
venient for the passage of the streams. and
seemingly designed for them ? The phenomenon
of rivers cutting through mountains and lofty
plateaus, instead of going around them, is COM
mon IN all great rivers of the world. Perhaps,
the most extraordinary instanc e is the Colorado
River, of the West.
The Colorado is only an extreme illustration
of a fact disclosed by a majority Though not by
all OF the great rivers of the world. They do
not avoid mountain ranges or high plateaus
which lie athwart their tracks, but cut through
them IN profound gorges or canOns. How were
these great pathways OF the rivers excavated ?
What power has opened these chasms to
allow the rivers TO pass 70 this question,
geology gives US a complete and convincing
answer, which appears when we come to analyse
two propositions. The first is that rivers cut
and maintain their own channels. The second
is that those rivers which cut through mountain
ranges and plateaus existed before those
mountains and plateaus were reared.
y person examining the rivers of the Atlantic
States woalI see no reason to believe that they
are cutting down their beds. He would be quite
right. Those rivers have accomplished their
work and have cut down their channels so far
that they cut no more. But Ia the West the
truth Is quite otherwise. Excepting the lower
portions Of the Sacramento and San Joaquin. all
the western rivers are cutting down then beds.
The tools with which TIE river works are the
sand and grit suspended in its waters. It's action
is Identical ~ principe with the well-knoWn in
strument call 4 the sad blast. Under favorable
conditions th,s action becomes Very rapid q ID
enc. G"t.g. l. one Of the hydraulic mines of CAL
ifornia :he ,~~earing waters cut into the basaltic
bed rock 1T the rate of Is feet per annum.
The quantity of debris which a river carries is
called its load" It's ability to carry sediment
is termed its transporting power" This power
depends chiefly upon the velocity of the stream
and the velocity again depends upon the de-
clivity of its bed. Where the d~eclivity is great
the velocity and consequent transporting power
are also great, and the bed rock is kept bare and
subject to the grinding action of the sand blast.
Where the deelivity Is small the velocity and
transporting power are small; sediment is drop.
ped and forms a protecting cover to the bottom.
All rivers tend to the establishment of an
exact adjustment of transporting power to load.
1t does this by cutting down its declivity every
where, until the velocity and transporting power
are so reduced that they begin to drop sediment
on the bottom, and protect it from further wear.
When this stage is reached, the rivers grade iii
not subject to external disturbances) is in stable
equilibrium, and persists without change.
Many rivers have reached this condition.; notably
the Hudson and Mississippi. 1t is termed the
condition of base-level.
Causes sometimes intervene to disturb q base.
laval after II hac ha N aCtah Icha1 For 1oofonaa
suppose the land along its course to rise. This
increases the declivity, increases the velocity
increases the transporting power. The river
resumes it's work of cutting down it's bed, until
the lost equilibrium is restored. Or suppose the
land to sink. The declivity is diminished, the
velocity and transporting power reduced, and
more sediment is deposited, building up the bed
to the required deelivity until base-level is again
attained.
The eastern rivers are either in the stage oil
b~ase-level or very near it. But western rivers
are far from it. In the west, the declivities oil
the channels are very great. Consequently, the
bed-rocks are bare, and the turbid waters grind
them with n power which is evident to the most
careless observer. The cause of the difference
between the eastern and western rivers is soon
stated. The eastern country is an old region
geologically, and has been but little disturbed in
recent periods. The western country has until
the most recent epoch been n rising country thus
keeping up the declivities, and giving the rivers
more and more work to do.
The speaker then proceeded to apply this
beautiful theorem to some of the active rivers,
notably the Colorado. showing that the rise of &
mountain range or plateau, only provokes q
river to attack it and cleave the mountain asundel
and thus maintain its right of way. Other ap,
plications were given. One of the striking
thoughts deduced, was the antiquity of the great
rivers of n continent. They are older than thu
mountains or high plateaus, indeed, among the
oldest of its topographic features. Amid al
changes they alone have remained with compara
lively little change.