, 1891-08-21
GLACIERS IN DAKOTA.
COURSES OF THE MOVING ICE NOUN.
-AINS EASILY TRACED.

Fhcts which Seem to Show That the
Missouri River Has Changed Its Bed.
The Mystery of the Old Limestone
Bowlders-whencs cometh They9
North Dakota presents a very attract
i've field for every geologist and man of
scientific turn of mind, particularly in
the evidences Of the glacial period that
are so abundant on every hand. The
hills, valleys, lakes, rivers and the in
Vulnerable powders that lie scattered
over the prairies, the fertile soils, the
crop thereon, the climate, fauna and
flora all tell in the plainest language of
the great changes and influences wrought
by the passage of the glaciers southwark
Their effect on the confguration of the
landscape i've been tremendous, chang
ing and reconstructing the surface of the
country on a grand scale. The glacial
direction has been generally south and
west.
The granite powders, some of which
are very large and show but few evi
dences of grinding, are not SO difficult to
o for, but what is puzzling to the
inquirer is the origin of the limestone
powders that are profusely scattered
among the granite rocks. Limestone is
the product of deposits of animals-or-
ganisms whose abode was in the ocean.
Where these limestone powders now
found on the prairies came from is hard
to determine. The origin of glaciers is
always in elevations-regions where
there are mountains and valleys.
The vast and level plain lying north as
far az tho arctic nraan inc1Y,lin~ tha
Hudson bay country, over which the
glaciers have passed, does not present
the conditions which are necessary to
glacial formation and progress. Profess
sor Hay thinks that different levels have
existed from which were begun the gla-
ciers that have passed over North Da-
kota.
II OLD BED OF H MISSOURI.
The limestone powders which are con-
hnual puzzles to the geologist present
many evidences of oceanic origin. There
are numerous fossil remains found in
them-mollusks that lived in the old ST.
lurian age, way back in the early peri
DDS of the formation of the earth's crust.
These powders must be of very ancient
origin, because as far as noticed they
contain fossils of the early and simpler
forms characteristic of those eras
Among these fossils are the ~trilobites,
one of the commonest of the extinct spe-
cies of mollusks that flourished in palea-
zoic times.
The course of the glaciers southwark
is plainly marked east Of the Missouri
river. West of that stream there are few
or no deposits of glacial drift. Princi-
pally on this account, Professor Hay
says that it is not improbable that the
Missouri river ono ran through the
center Of the two Dakotas, possibly
where the James river valley now marks
a long and noticeable depression in the
surface of the country, and that the
present turbid and crooked stream has
been literally pushed westward to its
present channel by the ~encroaching forces
of glaciers slowly moving southwark and
filling up the depressions of the tract
covered with the materials'conveyed by
them.
The great river, which has its source
in the mountains, fed by streams of melt
ing snow and ice, probably ran eastward
as far as DEVILS lake, before taking
its old southerly course. The only gla-
cial drift found west of the Missouri is
near the mountains and came from them,
while the drift east of the river belongs
to other distant and different formations.
ORIGIN OF MANY LAKES.
The present existing streams, valleys
and coolies nave beer formed by the
washing of great streams of water that
AVE followed the melting of the glaciers.
The water flowing over the deposits left
by the glaciers-earths and shales that
were softened and easily disturbed-has
washed out the valleys and left the pres
emit uncomfortable streams such as the
James and Cheyenne rivers. The drift
OF diluvium deposited by the glaciers is
easily noticed in the coolies and valleys,
along the upper ridge of which are seen
denominations of powders. The reason
why a line of powders nearly always
marks the top of the sidss of the valleys
is that the other powders originally left
in the soil washed away, have also been
carried off by the rush of water.
1t is not believed by Professor Hay
that the presence of the large number of
powders that lie piled thick on the
shores of May of the lakes of this state
can be accounted for by the action of
freezing and thawing which has pushed
the rocks on the shore. He thinks that
many of the present lakes have been the
stopping place of glaciers. Some change
in the temperature arrested the rogres
of the ice field, which was again started
forward by a sudden melting, and the de-
pressions left in the surface, fioored with
an unusual deposit of powders, are now
our beautiful lakes.
This action of the glacier can be dis
tinctly traced in South Dakota, where
thRra ara naar Huron Gayarnl localities
showing distinct evidences of where the
glacier rested, left its monuments of
rounded and polished rocks to mark the
spot and again moved under the impel-
ling heat of the sun. The progress of
this glacial march can be distinctly
traced from point to point by lines of
powders and other indications known to
biologists. jamestown IN. d. Alert.