May 20, 2013

Chicago Geography and Glaciers

Chicago's natural geography is a result of the large glaciers of the Ice Age that carved 
out Lake Michigan (which formed from the glacier's meltwater). The city of Chicago is 
a flat plain that was once the bottom of ancestral Lake Chicago.

During the last ice age the Glacier over Lake Michigan was one mile high. When it 
melted it formed a very large river valley along the Des Plaines and Illinois Rivers. 

The highest point within the city limits is in the Beverly neighborhood. In pioneer days, 
this hill was called Blue Island, so named because at a distance it looked like an 
island set in a tractless prairie sea. In fact it, and the nearby Stony Island, were 
both islands in Lake Chicago, as it receded. On the North side, the diagonals 
Clark Street and Ridge Boulevard run along ridges that were once sandbars 
in the Lake.

One special feature of the Chicago area was the now-vanished Mud Lake in the 

Des Plaines Riverwatershed. During heavy periods of rain or when the Des Plaines 
overflowed its banks due to downstream ice dams in the early spring, the river would 
flow through Mud Lake to the South Branch of the Chicago River, forming a favorite 
portage for early traders and creating the path of the future I&M and Chicago Sanitary 
and Ship Canals

When the city we know today was initially founded in the 1830s, the land was swampy 
and most of the early building began on low dunes around the Chicago River's mouth. 
Indeed, Chicago's low lying geography, which ultimately became crucial to its boom 
town development (as the site of the Chicago Portage and canal), could not initially 
attract substantial early settlement because the tall grass prairie around its lake and 
river systems was underlain by hard packed glacial clay, making much of the area 
forbidding wetlands.[1] Thus, the paradox of Chicago's development as a city in the 
19th century became taking advantage of this geography, but also overcoming its limitations.

North of the city of Chicago, there are steep bluffs and ravines that run along Lake 

Michigan. In contrast, south of the city of Chicago into Northwest Indiana it is without bluffs, 
but instead has sand dunes. The greatest example of these can be seen at Indiana Dunes 
National Lakeshore, where some dunes reach up to almost 200 feet. Farther inland, a series 
of moraines surrounds the Chicago Plain. This surrounding area is hilly and higher than the 
Chicago Plain. Past the moraines, the land flattens out again, but is interspersed with a few 
deep river valleys such as the Illinois RiverFox RiverDes Plaines River, and Kankakee River
Here you may find rock cliffs and rock ravines, which are absent from the interior Chicago area 
(the ravines of the north shore and south suburbs are soil ravines without any rock).

City limits of Chicago

Also, a very large limestone quarry (Thornton Quarry) exists just south of the city of Chicago 

in the suburb of Thornton. It was once a coral reef when the Midwest was covered by a warm 
inland sea (hundreds of millions of years before the glaciation of the Chicago area). The 
rest of the Chicago area does not have bedrock this close to the surface.

  1. Geography of Chicago - Wikipedia, the free encyclopedia
    Chicago's present natural geography is a result of the large glaciers of the Ice Age, namely the Wisconsinan Glaciation that carved out the modern basin of Lake ...
  2. Glacial Lakes - Department of Geography - Michigan State University
    Initially, excess water from Glacial Lake Maumee flowed southwest to the Wabash River, and Glacial Lake Chicago drained west and south by way of the ...
  3. Glaciers - An Overview of Glaciers - Geography -
    A comprehensive overview of glaciers. Includes the types of glaciers, how glacierscarve the land, and the importance of glaciers. From Colin Stief of Geography ...

  4. The Elementary School Teacher and the Course of Study - Volume 3 - Page 573 - Google Books Result
    Hills, valleys, and plains — due to glaciers. Contributions of glaciers to the localgeography of Chicago. (Study of work of glaciers at Cary, Glencoe, and Stony ...

  5. Bulletin of the Geographic Society of Chicago - Issue 1 - Page 19 - Google Books Result
    Geographic Society of Chicago - 1920 - Geography
    Geographic Society of Chicago. been called interglacial. During the glacial epochs the climate was severe, and the ice-sheets were enlarged; during the ...
  6. Geography of Palos Hills, Illinois
    Geography of Palos Hills, Illinois ... That extensive area of water was called glacialLake Chicago. It is right here in the Palos area where the moraines broke and ...
  7. BBC - GCSE Bitesize - Glacial landscapes and processes › Home › Geography
    A secondary school revision resource for GCSE Geography on the topic of glaciallandscapes and processes, glacial deposition and erosion.
  8. What role did glaciers play in shaping the physical geography of ... › Categories › Society & Culture
    Chicago's present natural geography is a result... 436 days ago. What is the role ofGlacier Park International Airport? Glacier Park International Airport is loacted ...
  9. Chicago Geology - Faculty Home
    In the Chicago region, glacial melt was dammed first by the Lake Border Moraine. ...Another major change in the geography of Chicago occurred with the in ...

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