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The geology and hydrology of the area was determined my the great ice
sheets that covered the area during the ice age. The advancing ice
sheets pushed up what are called terminal moraines, which are pushed up
ridges of dirt and gravel scraped up by the ice sheets. There are a
succession of them that run approximately parallel to the present shore
line of southern lake michigan but several miles inland and up to about
30 miles inland. These moraines then contained the water that was left
when the ice melted in a lake that was larger and higher than present
Lake Michigan and has been named Lake Chicago.
At some point erosion did cut through the moraines and caused the water
from lake chicago to run off creating the Illinois River valley and
draining down the Mississippi and causing the level of Lake Chicago to
drain in three successive stages each lowering the lake level
approximately 20 feet. This can be seen by driving west from the shore
line. Chicago is as flat as a pancake because the land used to be the
bottom of  Lake Chicago. As you drive west you climb a ridge 20 feet
high at about Naragansett Avenue which is about 8 miles inland, this is
the first moraine. Going further west you climb two more moraines until
about 30 miles inland.

The Chicago river has two branches, one running north and the other
southwest which ended about 10 miles inland, at Harlem Avenue just to
the east of the first moraine. This moraine is narrow at this point and
less than a mile to the west is the Des Plaines river which runs north
and south and joins the Kankakee river which then forms the Illinois
river which then drains into the Mississippi. The Chicago river empties
into Lake Michigan down town. The Des Plaines does not drain into Lake
Michigan because of the moraine.  So if you peed on Harlem Avenue, about
10 miles inland, it would have drained either into the Mississippi or
into Lake Michigan

This configuration of the southwest branch of the Chicago River coming
within a mile of the Des Plaines River permitted a short portage for
canoes. A canal was completed in 1848 named the Illinois and Michigan
Canal (the "I&M Canal" ) which permitted river boats to travel from
Chicago through this area and into the Illinois River. This canal
parallels the Des plaines River for about 50 miles until it joined the
Illinois river where that river was deep enough for navigation. The I&M
Canal is still there and runs about 200 meters east of the Des Plaines
River for most of its length. It is narrow and is now used by
recreational canoeists. I assume that this is "the old canal"  in your post.

A much wider and deeper canal was completed in 1900 called the Chicago
Sanitary and Ship Canal. One of its main purposes was to reverse the
flow of the Chicago River to prevent polluted runoff from flowing into
Lake Michigan which is the water supply for the city. This engineering
was accomplished to end repeated cholera epidemics. There is a lock now
at the mouth of the Chicago River that prevents unrestricted flow out of
the lake into the river. This was touted as one of the "wonders of the
world" and required moving more dirt than the Panama or Suez canals.
This canal parallels the I&M Canal for  most of its length. So now,
after 1900, if you pee on Harlem avenue it will certainly run into the
Gulf of Mexico. This canal now carries much barge traffic and is one of
the reasons Chicago is so successful due to the low cost of this method
of transportation. Neither it nor the Illinois river are navigable by
ocean going vessels.


If you are more interested in this I can recommend a book written by my
friend and my former geography professor at the University of Illinois
in Chicago called "The Chicago River" by David M. Solzman.

Gary LaPook


George Huxtable wrote:

> To be honest, this isn't really a question about navigation, but about
> geography and hydraulics. But some Nav-l contributors hail from the
> Illinois
> area, so perhaps know the answer.
>
> I've been reading an odd book, published in 1911, The Log of the "Easy
> Way".
> This is about the voyage of a young couple, in 1900-01, in a
> house-boat or
> "shanty-boat", drifting down the Mississippee to New Orleans. The journey
> started in Chicago, with a tow through the "Old Canal", which
> presumably was
> later enlarged into the present Ship Canal. Then down the Illinois
> River to
> the Miss.
>
> The book took my interest as it took in the same stretch of the Miss.,
> between St Louis and Cairo, as had been used by Lewis and Clark, a
> century
> before, to reach their official setoff point.
>
> I'm aware of (and have always been rather puzzled by) how close the
> drainage
> of the Miss. basin comes to the Great Lakes, West of Chicago, but have
> presumed there's a narrow watershed, close West and South of Lake
> Michigan,
> which prevents that lake from spilling over to end up at New Orleans.
>
> And yet, in this book, the author, having reached the Illinois River,
> comments after passing La Salle / Peru, that "Its water may come from the
> cold, clear depths of Lake Michigan but ... ".  Surely not, I surmise. If
> that had ever been the case, the watercourse would have eroded over the
> millennia to become, by now, a torrent. Is it even hydraulically
> possible,
> even if the ground West of Lake Michigan is permeable to underground
> flow?
> That would require the water level in the upper Illinois to be lower,
> with
> respect to sea-level, than is Lake Michigan, at 580 feet? Is that the
> case?
>
> Presumably, there's a dividing line somewhere, on one side of which,
> if you
> pee on the ground, it will end up in the St. Lawrence, and on the other
> side, in the Gulf of Mexico. How far do you have to travel from Lake
> Michigan, to reach that line? It's not an important matter, but it
> interests
> me.
>
> George.
>
>

   

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