Wood County reporter. [volume] (Grand Rapids [i.e. Wisconsin Rapids], Wis.) 1857-1923, 1888-07-05
LAKE MANUFACTURE.
How North American Lakes We're
Made-ScO0ped Ont by Enormous
Glaciers-An Ice House From
Maine to Minnesota.
The Science of Geology Explains
World of Wonders.

4 glacier Is aptIy called q river OF ice.
Like river of water it has an upper sur
face sloping continually from source to
goal. and like river Of water, is rests on
an uneven bed of its own shaping. When
an AQUEOUS river is suddenly deprived OF
its supply Of water, there remains along
lis channel series of pools recording
the inequalities of erosion When a
great glacier is melted away the iuea uali-
ties of its erosion are recorded to a chai2
of lakes. Moreover, much of She materi
al ground and torn by the glacier from
It's bed Is carried forward in the ice and
dropped in long heap where the ice
melts, constituting moralne. If the
final melting is gradual, a series of mo-
raines 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
and the surface of the moraine is made
billowy Astounding in small lake basins.
Thus from glacial erosion there arise
rock basin lakes, and from glacial depo-
sition of detritus there arise moraine
dam 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
tinent was so great and the annual melt
ing was so small that the snow accumu-
lated year by year, and became cemented
into a continuous, deep and ever-growing
sheet of ice. AS the depth of the sheet
increased the pressure of its own weight
became finally insupportabIe, and there
was relief by horizontal flow, the moraine
mt arG fn Of
climate, where it was melted, 1t was, in
fact, a vast glacier, so vast that the figure
of speech embodied in the title ''river of
ice" becomes here inapt. Instead of flow
ing from mountain down a sloping val
ley, it flowed rapidly from q 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
persion, 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 wnen the sun finally surveyed
its reconquered territory, the land was no
longer simply craven with a tracery of
llN0Is3 u : pdAhCAOu Will bIS Su66u VI III
Vulnerable lakes.
But the theory of the lakes is not COM
pletely told by explaining the origin of
their basins; there is also a 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 Susquehanne and the Della.
ware. AS encroaching heat gradually
reduced the limits of the ice, its retreat
ing margin reached and passed the basin
rim at various points, and there accumu-
lated between the water parting and the
ice wall a 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, buG 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, th ere
was time when the southern part of the
Michigan basin held 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 al
Fort Wayne TO 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 Ontario.
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