The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1889-10-30
ARE WE DISAPPEARING
The Wearing Away of the Earth by the
Action of River and Sea.


Action of River and Sea.
Resistless changes are in progress
the whole world over; and though we
seem to be now happily free from those
dire commissions which in past ages
engulfed continents, and raised others
from the deep. the slow but relentless
wearing away of the land surfaces OF
the globe goes on night and day; every
storm that blows, every shower that
falls, adds its share to the work; and
though the fate of islands that have
disappeared may never befall any
existing land area of substantial size,
the mean height of the land above the
sea is yearly decreasing, and it is more
than probable that the actual area
is also growing less For example.
the tearing away of the soft
cliffs of some of our Eastern counties
may be compensated for in part or by
sitting up of shallow estuaries, or the
gradual addition of land at other
points; but there is no doubt that a
considerable portion of this matter is
carried to sea and helps slowly to fill
up the ocean depths. AS to the capac-
ity of those depths there is unques-
tionably room enough therein to en-
gulf every atom of dry land, and still
to leave many scores of fathoms of
water over the surface of the globe.
But the rate at which the process goes
on by means of the action of tides and
ocean currents, though extremely rap
id at certain points, both on our own
coasts and elsewhere, is, on the
whole, of little comparative import
ance. 1t will neither deprive US,
within practical period, of
any considerable area of valuable land,
nor will it fill up to inconvenient shall
lowness any of the navigable seas. If,
however, we enlarge the subject to
that of land denudation, and the sitting
up of the ocean depths generally, we
have an intensely interesting theme.
Every river-every little rill that
trickles from the higher lands-carries
down its contribution of organic and
mineral matters. The hardest rocks
even are disintegrated in time by the
action of rain and frost, and every
thunderstorm or heavy fall of rain
burrows the hillsides and charges the
food-waters heavily with solid mat
tiers, which when carried out to sea are
slowly deposited. The Challenger expe-
dition found these deposits at distances
of about $50 miles from the nearest
land; while the amount of solid matter
which such streams as the Mississippi,
the Amazon, the Congo, the Nile and
the Yellow river of China carry to the
sea in a year is scarcely credible 1t
has, however, been calculated that on
the average, as nearly as possible, riv-
ers on entering the sea contain %
grains of solid matter to the cubic foot
of water; and from this the following
curious results are obtained. The
Rhine, fairly average stream, carries
to the sea 145, $50 cubic feet of solid
matter per day; and the proportion,
applied to all the rivers of the
earth, comes to roundly 1870 cubic
miles of matter per annum.
Carrying the calculation a little
further, on the basis of an average
height of the dry land above the sea
level of 600 feet we find that this
average annual loss is equal to 1,170
square miles of the earths surface.
1t does not follow that the earth's dry
land area is diminished by that
amount, but simply that the actual
mass of solid matter above the sea
level is annually diminished by a mass
of matter equal in area to the entire
county of Kent, and to an average
depth of $50 feet. It further means
that if the whole of this energy could
be brought to bear on the British
Islands alone, they would disappear in
less than century, even if the tides
left our coasts untouched Yet
again, taking the entire dry
land surface of the earth at an aver
age elevation of 600 feet, as before,
above the sea level, we have a total
mass of matter not exceeding six mill
ions of cubic miles. Then, assuming
the present rate of wearing away to go
on by river action alone, i. e., $50 cubic
miles per annum, we should have as
the result, at the end of about As, 900
years, that the entire land surface of
the globe, save few isolated peaks of
the more durable rocks, would have
disappeared-th said peaks, like that
of Teneriffe, standing grim and solitary
guardians over an otherwise unbroken
waste of waters. -London Standard.