The Washington times., 1901-07-14

ed. is characterized by a progressive
change in the attitude of the land, the
northern and northeastern portions OF
the region becoming higher, SO as to
turn the waters more and more toward
the southwest The latest change, from
Great Lake Nipissing TO Great Lakes
Superior. Michigan, and Huron. invoiv-
ing an uplift at the north of more than
100 feet. has taken place within 50
short a period that it strongly sug-
gests the question whether or not the
uplifting process is still going on.
THE PROCESS STILL PREVAILS.
This question has been tested by the
United States Geological Survey, with
the result that all indications ioint to
the conclusion that the fitting process
of the northern and northeastern por-
tions of the region still prevails, and
that the encroachment of the southern
and southwestern coast lines of the
Great Lakes is under constant, though
slow, process of extension, that is, that
the area of the Great Lakes is increas-
ing all the time. Lake Ontario Tes al
together southwest of the base of its
outlet. and the water is encrcacEing on
all its shores. The same fitting that en-
larged it is still increasing its extent.
The estimated vertical rise at Hamilton
is 6 inches per century. The whole coast
of Lake Erie also is being submerged,
the estimated rate at Toledo and San
dusky being or g inches per century.
All coasts Of Lake Huron are rising
as compared to the outlet, and the con-
sequent apparent lowering of the mean
water surface is estimated at s inches
a century for Mackinac. and at 10 inch
es for the mouth of the French River,
on Georgian Bay. At Escanaba, the es-
timated fall of the water is 4 inches per
rise is or inches. and at Chicago be-
tween and 10 inches.
These slow changes of mean water
level are concealed from ordinary OBJ
servation by the more rapid and inn
pressive changes due to variations of
volume, but they are worthy of consid-
GRAFTON in the planning Of engineering
works of a permanent character, and
there is al least one place where their
influence is of moment to a large COM
munity.
A MENACE TO CHICAGO.
The city of Chicago is built on
smooth plain. little above the high
water level of Lake Michigan. Every
decade the mean level of the water is
an inch higher, and the margin of safe
ty is so narrow that inches are vaIu-
able. Already the older part of the city
has lifted itself several feet to secure
better drainage.
The time will surely come says Mr.
Gilbert. when other measures of pro-
lection are imperatively demanded.
Looking to the more distant future,
we may estimate the date at which
the geographic revolution will occur.
Near Chicago is an old channel made
by the outlet Of a glacial lake. The
bed of the channel at the summit of the
pass is about eight feet above the mean
level Of Lake Michigan and five feet
above the highest level In 500 or 600
years (assuming the estimated rate Of
tilting) high stages of the lake win
reach the pass. and the artificial dis
charge by canal will be supplemented
by an intermittent natural discharge.
In 1000 years the discharge will occur
al ordinary lake stages, and after 1,590
years it viii be continuous. In about
1000 years the discharge from Lakes
Michigan, Huron, and Erie, which viii
then have substantially the same level,
VIII be equally divided between the
western outlet at Chicago and the east
ern at Buffalo. In $500 years the Nj
agara River viii have become an inter
mittent stream, and in 3,OOo years all its
water will have been diverted to the
Chicago outlet-the Illinois River. the
Mississippi River, and the Gulf of Mex
icnn