The Grit-advocate., 1903-12-18
MinncSota'S Old
Volcanoes
Tremendous Eruptions Once In 4
Now Level Region.

Most of the natives of Minnesota have
come East over the Appnlachians the
great hills are IA wonderful and inspiring
revelation. Their own state has ie"
groups of conspicuous hills and many
bluffs along the Minnesota and some
other rivers, but as a whole the state
consists of undulating prairie land.
The ordinary observer would never sus-
pect what is a fact. that the territory now
occupied by Minnesota was formerly
shaken by tremendous crupions from
volcanoes, whose necks or conical mounds
cannot now be even found; or that it had
towering mountains which have been
worn down until only their hattened
stumps remain. But seologlsts tell us
that the Minnesota mountains were once
high and grand.
These facts were not discovered until
recent years. since the geologlcal survey
of Minnesota was organized. The sclen-
tific men of this survey have made IA
very careful survey of every part OF the
state and revealed the wonderful story Of
the ancient land.
Prof c. w. Hall. who occupies the chair
of geology and mineralogy in the Univer-
sity of Minnesota, tells us in "A book he
has just written that the volcanic phe-
nomena of Minnesota were, in their time,
on a scale more magnificent than even
in Italy. Hawaii and the Philippines,
where. as we know, tremendous masses
of lava have been poured out of craterS
to cool as basalt. The lava streams OF
Nesuvius cover only "A paltry few square
miles only 1000 square miles of Hawaii
are covered with volcano outpourings.
But in Minnesota. as Prof. Hall relates.
over 5000 square miles are "overspread
with rocks dark in color and as genu-
incly volcanic as are those Of Nesuvius
or kilauea. and thousands of square
miles carry more GRANTEES and other
rocks that tell the story of stupeEdous
action long geologic ages ago
The region of Minnesota has many
times been shaken by volcanoes. -Four
periods of eruptive activity may be count
ed in the rocks as one walks the streets
of Duluth.
in walking from the mouth of the St
Croix river up through the streets of
Taylors Falls, which stands on its banks
The town of Chenrwatana stands on a
sheets of lava may be counted
The city of st. Cloud. on the upper
se ana Is o .hs by
tremendous earth forces Along the
northwest shore of Lake Superior were
"A series of ancient volcanoes that poured
out enormous lava flows, built up beds
of volcanic ashes. or injected molten ma :
terial as broad dikes within the older
rocks.
We know that the crust of the earth is
continually moving up and down. SO
slowly that any apprcciable change in
level may not be revealed for centuries
These changes of level may best be OBJ
served along the margins of the sea, and
We know that part of our Atlantic
SGaI Wb IS re no" very cry ssrndTiaiy sinking
are rising.
The Minnesota biologists tell us that
parts of the state are rapidly sinking
The Root river. for example. seems to be
slowly sinking about its mouth. The
geoogis,s infer this because hundreds of
acres of marshy land have been formed
around the mouth and along the lower
part of the river
Having dropped to little lower level
the river. of course. has lost impetus near
the place where it joins the Mississippi
and so the slit it carries has dropped
within its own flood plain. forming the
marshes that are gradually growing 1t
is also believed that the Mississippi river
is slowly sinking about its head waters.
If this proves to be a fact the navi-
gable stretches of the Mississippi above
Minneapolis will become less useful. be-
cause the slowly flowing waters will load
the bed of the river with detritus and
make it less available for transportation.
we, speak of the. Mississippi the
have proved that its aiiluent the Mime
sofa river. is entitled to be called the
grandfather of the Upper Mississippi.
unites with it, at Fort Smelling They
know that this is true, because the great
valley of the Minnesota shows that it has
been deepened and widened by the work
Of many ages. while the neighborng val
ley of the Upper Mississippi is a new.
narrow. clean-cut groove which has not
yet had time to dig away its banks and
make broad valley miles in width like
that through which the Minnesota flows.
These are only few of the interesting
facts that have been revealed within the
last few years by a careful study of the
geology of Minnesota. They show how
history of the surface we occupy may be
deciphercd and made intelligible by the
methods of modern science.-New York
Sun.