The daily journal. (Salem, Or.) 1899-1903, 1901-12-17
WEAR OF THE EARTH
HOW THE FACE OF OUR GLOBE IS
CONTINUALLY CHANGING.


The atmosphere plays its part in geo
logical operations. It's corrodlng pow
er, backed by rain and wind, helps to
decay and disintegrate those rocks
which are exposed to its influence. Rain
completes the work thus begun. Wind
blows dust, sand and volcanic ashes
over large tracts Of earth-in fact,
over the whole of II.
1t Is only of late years that geolo-
gists have discovered that fine vol
canic dust Is carried over the whole of
the earth's surface anu plays a very
important part in the deep sea depos-
its. On deserts and nearly ralnless re-
gions blown sand will wear away the
hardest rocks by beating against
them. Some sandstone formations APP
pear to have been piled up by winds.
Winds cause ocean currents, waves
and storms. The great denuding
power of the sea is largely due TO the
atmosphere. Some parts Of the Eng
llsh coasts are being rapidly washed
away. Plants and animals have their
distribution considerably affected by
winds and ocean currents. Again,
whether living In water or on land,
animals live on the oxygen supplied
from the atmosphere, and land plants
absorb carbonlc acid from the same
source.
Rain acts in two ways: Q) chemic-
ally by dlssolving certain substances
such as lime, out OF the rocks, and (2)
mechanically by wearing down their
surfaces as II flows over them. Any
old building-a ruined castle or cathe-
dral for instance-shows a "weath-
cred" surface resulting from the ac-
ton of rain and wind. In sandstone
structures the details OF carving are
often lost, and on old tombstones the
lettering can hardly be declphered.
Springs are due to rainwater collecting
in rocks and rising to the surface.
Rivers are fed by rains and springs.
A river is very powerful geological
agent. In the hardest rocks rivers
gradually carve out valley or gorge.
This is accomplished partly by chemc.
ally dissolving certain mineral sub
stances, but chiefly by mechanical
erosion, the stones, sand and mud
wearing uway the bed OF a stream as
they run and tumble over 1t.
The finest examples OF river action
are the famous canyons of Colorado,
which In some places are gorges 5000
or even G,OO0 feet deep, with vertical
sides. But, rs already pointed out,
rivers have constructive action quite
as important as their destructive ac-
tlon. by bringing down their burden
of sediment into lakes, estuarles and
seas they bugd up great piles of rock
and "sow the dust of continents to
be-"
Glaciers are rivers Of ice fed by the
eternal SHOWS" of high mountain
ranges such as the Alps. They wear
out their own valleys as rivers do;
they transport mud, sand and stones to
great distances In some cases sending
them sealed up in icebergs to float far
out 20 sea and on melting deposit their
burdens on the sea floor. on the coast
of Newfoundland northern icebergs
are deposltlng great mass Of "gla.
clal drift"
The sea is a great denudng agent;
but it's work Is more constructive than
destructive. 1t is the workshop where
nearly all the stratihed rocks have
been accumulated and ranged I'm layers
or strata. The rivers and ocean cur
rents continually bring In fresh sup
81, Of hnnnraIa pf
miles
Man. compared with the lower AMI,
mails produces but little effect as a ge-
ologcal agent. Still the human race
has considerably modified the dlstrlbu-
tion OF plants by cutting down forests
and by cultlvating certain plants to
supply food. So with animals. Ger
tain useful species have been cultlyat'
cd and enormously increased at the
expense OF others which prove useless
or harmful.
But plants and animals have had
aud still have. FAR more influence geo
logically. Coal seams are made up %
vegetable remains OF former periodic
Forests have an important Influence
ON climate and on animal as well as
plant life. In the comparatively un'
known world OF the ocean marine
plants doubtless have important func-
tiOus.
Marine animals accomplish vast
amount Of geological constructive
work. Great deposits thousands or
feet thick owe their existence To small
calcareous creatures living In the sea.
Coral reefs afford the most familiar
! illustration.
The force known as heat Is OF great
importance. The earth Is hotter below
the surface aud probably has n very
| high temperature toward its center.
I In some places not very far below Its
surface II contains highly heated rock,
which occasionally flows over the sur
| face during volcanic eruptiOns. In
other places we find hot springs In con
/ nection with volcanic action.
Heat exercises powerful influence
on rocks deeply buried below the
earths surface, chiefly by means OF
heated water and steam. Ina this way
rocks have been very much altered
or "metamOrphosed" The crystalline
schists have thus been brought to their
present state by series Of chemical
( changes due TO heat. and there Is No
doubt that they were once ordinary
deposits Of clay, sand, etc.-Hutchin
sons Autobiography Of the Earth
the Appleton Company.
An Unreliable Guide.
FYeddy-Ma, according 20 my appe