Iowa County democrat. [volume] (Mineral Point, Wis.) 1877-1938, 1888-06-29
LAKE MANUFACTURE.
How North American Lakes Were
Made-Scooped Ont by Enormous
Glaeiers-An lee House From
Maine 10 Minnesota.
Ihe Science of Geology Explains
World of Wonders.

glacier Is Hptty called river OF ice
Like q river of water it has an upper sur
face sloping continually from source to
goal, and like a river of water, it rests on
an uneven bed of its own shaping. When
an AQUEOUS river is suddenly deprived of
Its supply of water, there remains along
its channel series of pools recording
the inequalities OF erosion. When a
great glacier is melted away the iueauali-
ties OF Its erosion are recorded TO q chaiS
OF lakes. Moreover, much of the materi
81 ground and torn by the glacier from
its bed is carried forward in the ice and
dropped in long heap where the ice
melts, constituting moraine II the
hnal melting Is gradual, q series of mo-
ralnes partitions the valley, creating lake
basins. While it is building moraine,
the ice front advances and retreats in
response to small changes in climate, so
that the dropping of detritus is irregular
aud the surfGce of the uoraine is made
bLIowy Astounding in small lake basins
mus from glacial erosion there arise
rock BASIN lakes, and FROM glacial depo-
sltlon of detritus there arise moraine
DAN med lakes and moraine lakes.
In that wonderful geologic winter
known as the Age of Ice. the annual
snowfall on the northern part of our CON
tnent was so great and the annual melt
ing was so small that the snow accumu-
lated year by year, and became cemented
INTO continuous, deep and eyer-growinC
sheet of ice. As the depth of the sheet
increased the pressure of its own weight
became finally insupportable, and there
was relief by horizontal flow, the moraina
moving outward to a region Of warmer
climate, where 1t was melted, II was, in
fact, vast glacier, SO vast that the figure
of speech embodied in the title ''river of
Ice" becomes here inapS. Instead of flow
ing from mountain down q sloping val
ley, 1t flowed rapidly from central
plateau Of ice, with little regard for the
slopes of the land over which it passed.
We do not yet know the center of dis
perslon, but the ice entered our land as
an invader from Canada. The border
states from Maine to Minnesota were
overrun, and most of the land north of
the Ohio and Missouri rivers. Twice the
van was pushed far into the domain of
of the sun, and twice it was compelled to
retreat; but when the sun finally surveyed
its reconquered territory, the land was no
longer simply craven with a tracery of
rivers; it sparkeled with the sheen of in
Vulnerable lakes.
But the theory Of the lakes is not COM
pietely told by explaining the origin of
their basins; there is also history of
their development as water bodies. Dur
ing the period of greatest ice expansion
the photographic basin of the Great
Lakes and the valley of the st. Lawrence
wese not merely filed but over passed, so
that the rivers generated On the glacier in
summer fell from its southern edge be
yond the rim of the Great Lake basin and
flowed to the Missouri, the Mississippi
the Ohio, the SusquehaLna and the Della
ware. AS encrOaching heat gradually
| reduced the limits of the ice, its retreat
| ing marglA reached and passed the basin
| rim at various points, and there accumu-
| lated between the water parting and the
| ice wall series of glacial lakes fed by
| the melting ice and discharging south
ward across the passes of the great divide.
The precise order of events has not been
made out, bus there was time when the
western part of the Superior basin con-
tanned lake discharging into the Missis-
! sippI River by way of the ST. Croix, there
was a time when the southern part of the
| Michigan basin held a lake discharging
into the Mississippi by the way of the
Des PLANES and the Illinois, and there
| was time when a lake occupying the
western half of the Erie basin, and cover
ing tho Maumee Valley overlooked at
Fort Wayne 10 the Wabash River, and
thus sent its water to the Ohio. At a
later stage single sheet OF water covered
the southern part of the Huron basin and
all the Erie, and encroached slightly on
the Ontaria.
And so these lakes of ours, that seem
to ordinary observation as enduring as
the earth and yet as tickle as the weather,
are to the trained imagination OF science
both ephemeral and constant. The
geologist looks backward to the time
when they were not, and forward to the
time when they will no longer be; talks
of their birth, growth, decline and deaths
and comparing their span of life with
the earth's declares them evanescentl
The physical geographer, Analysing the
motions of the water, refers them to the
attractions of celestial bodies, the press
ures of air, the friction of winds, the
varying drynoss of the atmosphere, and
the varying rain, and assigning each
fluctuation to its appropriate cause, lays
bare fundamental constancy to which
the navigator and the statesman may
safely pin their faith.-The Forum.
CROTCH ON ITCHr Ointment cures Skin Hin