Bismarck daily tribune. [volume] (Bismarck, Dakota [N.D.]) 1881-1916, 1902-10-29
OF THE EARTH

WEAR OF THE EARTH
HOW THE FACE OF OUR GLOBE is
CONTINUALLY CHANGING.
Geological Agents That Are Always
Busy In Natures Great Workshop.
Where Man Has Comparatively Lit
tie Influence.
The atmosphere plays it's partin geo.
logical operations. Its corroding pow
er, backed by rain and wind, helps to
decay and disintegrate those rocks
which are exposed to it's influence. Rain
completes the work thus begun. Wind
blows dust, sand and volcanic ashes
over the whole Of it.
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 n plays a very
important part in the deep sea depos-
its. On deserts and nearly rainless re-
gions blown sand will wear away the
hardest rocks by beating against
them. Some sandstone formations ap-
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
ish coasts are being rapidly washed
away. Plants and animals have their
distribution considerably affected py
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 carbonic acid from the same
source. ~,
Rain acts in two ways: ~ chemic-
ally by dissolving certain substances,
such as lime, out Of the rocks, and ()
mechanically by wearing down their
surfaces as it flows over them. Any
old building-a ruined castle OF cathe-
dral, for instance-shows a "weath-
cred" surface resulting from the &C.
ton of rain and wind. In sandstone
structures the details Of carving are
often lost, and IN old tombstones the
lettering a hardly be deciphered.
Springs are due to rainwater collecting
in rocks and rising to the surface.
Rivers are fed by rains and springs.
A river is a very powerful geological
agent. In the hardest rocks rivers
gradually carve out a valley or gorge.
This is accomplished partly by chemic.
ally ~dissolving certain mineral sub
stances, but chiefly by mechanical
erosion, the stones, sand and mud
wearing away the bed of a stream as
they run and tumble over it.
The finest examples Of river action
are the famous canyons of Colorado
which in some places are gorges 5000
or ever 5000 feet deep, with vertical
sides. But, as already pointed out
rivers have a constructive action quite
as important as their destructive &C
ton. By bringing down their burden
of sediment into lakes, %estuaries an(
seas they build up great piles Of rocl
and ''sow the dust of continents II
be-"
Glaciers are rivers Of ice fed by tn
eternal SHOWS of high mountain
ranges such as the Alps. They weal
out their own valleys as rivers do
they transport mud, sand and stones t.
great distances, in some cases sendin:
them sealed up in icebergs to float faI
out TO sea and on melting deposit thci
burdens on the sea floor. Off the cOaS
Of Newfoundland northern iceberg
are ~depositing a great a of "gla
cia1 drift"
The sea is a great denuding' agent
but it's work is more constructive thai
destructive. 1t is the workshop wher
! nearly all the stratifed rocks hav
, been accumulated and ranged in layer
or strata. The rivers and ocean cur
rents continually bring in fresh SUP
plies Of debris even for hundreds o
miles. ,-
Man, compared with the lower an
mails, produces but little effect as a &c
illogical agent. Still the human rae
t has considerably modified the distribr
ton of plants by cutting down forest
q and by cultivating certain plants t
d supply food. So with animals. Gel
q tain useful species have been cultiva'
e ed and enormously increased at th
J. expense Of others which prove useles
It or harmful. -
d But plants and animals have ha'
|. and still have, far more influence ge'
t. logically. Coal seams are made up {
vegetable remains Of former period
Forests have an important in1uent
on climate and on animal as well 6
plant life. In the comparatively III
y known world Of the ocean maril
J. plants doubtless have important fun
= lions. ~e.
y Marine animals accomplish a va
e amount Of geological construct,
t work. Great deposits thousands
o. feet thick owe their existence to snln
calcareous creatures living in the st
ID Coral reefs afford the most famili'
lI,,ctrotiOn IE. go i-. ~