The record-union., 1899-06-18
cH|CAGO A DOOMED CITY.
BEING SLOWLY ENGULFED IN
LAKE MICHIGAN.
Gradual Tilting Of the Earth's
Crust in the Lake
Region

iolSSSor O n. SIllDerI contributes TO
the latest volume of the Geological Sur
vey reports some interesting revelations
about actual and possible changes of
level in the lake region of this coun-
try. Attention was first directed to this
matter in 1869, when Wisconsin sur
veyor noted that millrace at the east
ern end of Lake Superior was dry, while
there were evidences that along the
southern and western shores of that
body Of water the streams at their
mouths seemed to be little fuller than
ever. The phenomenon could be best
explained not by drouth that would
infect the whole lake surface alike. but
by general changes in the relative hight
of the different districts.
A notion of this sort has the partial
corroboration Of history. The geolo-
gists, in tracing the outlines of the Great
Lakes as they existed shortly after the
glacial period, and comparing these
with the present configurat ton of the in
land seas, are able to detect marked
differences. Moreover, they can see that
the terraces" left by subsiding waters
around Lake Ontario are about $50 feet
higher at the extreme northeastern end
than down at Hamilton and Lewiston
Similar evidence indicates that as COM
pared with the level at Chicago, the re-
gion. lying little to the northeastward
of the Georgian Bay in Canada has
risen 25O feet.
Scrutiny Of various reports that have
been made independently Of one another
brings to light the fact that most of the
streams which run into Lakes Ontario
and Erie along the western half Of the
south shore possess certain traits in
common. Well inland, they follow a
fairly steep grade and have cores
pondingly swift movement. On ap-
preaching the large bodies Of water into
which they empty, they become slug
gish, having been converted into estu-
aries or narrow bays. The popularity
here mentioned is a recognized sign that
a locality has been submerged. This
fact corroborates the testimony just re-
ferred to, but without proving that any
change of level is now in progress. A
fresh investigation was needed for the
latter purpose
Professor Gilbert has succeeded in en-
listing cooperation which has enabled
him to find out what has taken place
during the last thirty or forty years.
consideration, each pair being so made
up as to combine points lying on a gem
orally northeast-and-s southwest line.
These pairs included Sackett's Harbor
and Charlotte on Lake Ontario, Port
Colborne and Cleveland on Lake Erie,
Port Austin and Milwaukee for the HUI
rom Michigan Basin. and Escanaba and
Milwaukee for Lake Michigan alone.
Official records of water levels iat these
points were consulted. In some cases
it was possible to find trustworthy data
for period of nearly forty years; in
others for only twenty.
HOW MUCH THE SINKING is.
The results attained were as follows:
Relatively to Sackett's Harbor, Char
lotte sank OO61 foot in twenty two
years. This is trif1e under three
quarters Of an inch. The places are
ninety miles apart. Cleveland, rela>
lively to Port Colborne, 16O miles away.
sank 2B inches in thirty-seven years.
Milwaukee, as compared with Port
Austin, 25O miles off, sank Obs foot
Il GAG inches) in twenty years And, as
compared with Escanaba, 100 miles dis
tant, Milwaukee sank 1073 foot (over
two inches in twenty years. Thus Pro-
fessor Gilbert is led to conclude that
along line running ~ degrees west
Of southwark there is mean subsi-
dence taking place now amounting to
O.42 foot for every hundred miles.
Eventually, 1t Is hoped, more elaborate
measurements may be made, .and more
accurate conclusions derived from the
observations But. as the matter now