Knoxville journal. [volume] (Knoxville, Iowa) 1874-1986, 1875-10-28
The Geological Importance Of Our
Western Explorations.

Western Explorations.
In no period of the worlds history has
there been greater activity displayed ia
enterprises 10 increase the knowledge OF
our globe and its history than at the pres
emf day; as instances OF which may be
cited the explorations in Central Africa,
those OF the ruins Of the cities Of antiq-
uity. such as Nineveh, the expeditions TO
the north pole, intended TOR settling the
| mystery of an open polar sea, the deep
sea soundings in the Pacific Ocean, prov
ing the existence Of sunken continent,
| and. last but not least, American explora-
lions in the great West, now in progress,
which have already contributed To our
knowledge of geology facts Of greater i'm
| portance than any obtained during the
previous half century. II is especially In
the region OF the Yellowstone River,
Astounding as it does with hot springs and
geysers, and in the valley Of the Colorado
that the most instructive features have
been discovered. While in the last few
decades the importance and universally
of slow upheavals have been demonstrat-
ed. the explorations have shown that a
second agent, namely, erosion, is OF the
utmost importance and results in variety
OF features, varying with the nature OF the
soil, the climate (wct, dry or rainless),
| uresence or absence Of winter frosts, etc.
In Colorado the erosion by the rivers
produces canons In the com paratively
easily worn-out rock of thousands Of feet
In depth; while the aTidity Of the climate
| prevents the rain from destroying the re-
suits of the erosion, as is the case in coun-
tries where rainfall is Of ordinary occur
renee. 1t is evident, therefore, that the
arid regions around the Colorado River
give specially favorable opportunities for
studying the effects Of erosion, and the re.
sent researches in that country have re-
suited in classification Of these effects, as,
/, the erosion OF water gaps 2, the cliff
erosion Of caDons %, hogbaek erosion, and
A, hill and mountain erosion. The sec
ond and third classes are due TO the I'M.
dcrmining action Of water in arid eli
mates while in the first and last this action
is modified by surface washings in rainy
or moist climates.
When another typographical feature Is
added, namely, the eruption and outpour-
ing Of molten matter from below, its
overflow covering the croded lands, and
It's subsequent erosion IN It's turn, new
Utll vi 40 pDthtag s5PttiAhy
instructive In arid climates, where sur
face washings do not destroy the promi-
nent points of interest This makes the
region OF the Colorado particularly rich in
peculiar features, such as canons and
canon valleys, volcanic caves and volcan
ic mountains, cliffs and hogbacks, buttes
and plateaux, naked rocks and drifting
sand, bluffs, valleys, etc. All the mount
A,,a ~.
being carved out by the running waters;
but, Notwithstanding the aridity Of the
climate in many localities, beds hundreds
Of feet In thickness and hundreds OF thou.
sands of square miles in extent, beds of
schist, granite, limestone, sandstone,
scale and lava have slowly yielded to the
unseen powers Of the air, crumbled away
into dust, and been washed away by the
rivers. 1t il an illustration on gigantic
scale of the return of the lands TO the
ocean depths from which they once arose.
II appears, however, that the climate
there has not always been so arid as 1t is
now; so the basin of the Great Salt Lake
which is now 80 depressed that its waters
have no outlet 10 the sea and are entirely
disposed OF by evaporation, leaving all dis
solved matter behind, had once moist
climate and so much rain that the valley
was filled with water 10 its brim, forming
d large and deep fresh-water lake which
had lis outlet into the Columbia River.
Mr.. G.. X. Gilbert, who studied the features
OF this outlet, considers its epoch identi-
cal with the glacial period; and from a
further study of the deposited soils he has
proved that before the glacial epoch an
arid climate prevailed there of many times
longer duration than the present epoch Of
100, 900 years which followed 1t.
The period of time required TO form
successive deposits OF thousands Of feet In
thickness, which the erosion of the Col
srado River has brought to light, in its
deep canons, Is enormous, and we can
not suppose that here the erosion was less
than that Of other rivers, although In
moist climates the evidences Of this ero-
sion have been destroyed; while In the
arid climates of our West they were pre-
served.
The evidences are that that region was
lifted up from the oceans bosom three
times that three times the rocks were
fractured; that three times the lava poured
out of the crevasses, and that three times
the waters carved out valleys in their
course seward. The first Of these periods
was after the formation Of the granite
rocks; the second succeeded the red sand
stone formation; the third period is the
present. The remnants of the first and
second periods are buried; but we know
that unnumbered centuries ago in the
past, the GRANTEES and schists, now on the
bottom OF the grand canon, were formed
as a sedimentary bed beneath the sea that
then an upheayal took place, after which
thousands Of feet Of beds were washed
away In the sea by rains; then a depres-
SION took place, sinking the whole region
some 10000 feet beneath the oceans sur
face, and allowing the formation of sand.
stone, at least 10000 feet In thickness, as
a sediment; then second upheaval came.
changing II again into dry land !;
then the rains washed away channels In
the sandstone 10, 900 feet deep, requiring
countless years Of gentle but unrelenting
energy. Again the sea rolled over the
land, which became Its bottom, and re-
ceived a new deposit of more than 10, 900
feet Of rocky bed; and lastly, this ocean
bed was again upheaved, and for 100, 900
years the atmospheric influences and the
running streams, gathered from the clouds
In the highest mountain tops, have been
making gorges canons and valleys, and
carrying the debris back To the sea, from
whose bottom the material all came.
Nc aEE VIII the xpu al Satun ft,turs,