Glacial Lake Chicago

Early Lake Michigan

Ancient Shorelines

This section refers to the phases of Glacial Lake Chicago.

The title “Lake Michigan” refers to stages that occurred after ice had completely left the basin.

3 Ancient Shorelines Glenwood Calumet Tolleston

Other events Two-Creeks Stage Chippewa Stage Nipissing Stage

Glenwood Phase

14.5 – 12.2 kya Lake Michigan began as a pro-glacial lake dammed

between the ice front and the moraines that circle the southern end of the Lake Michigan Basin. The lake overtopped the moraine in what is now

southwestern Cook County and rapidly eroded an outlet (the Sag Valley) nearly a mile wide.

Glenwood Phase was 55-60 feet above the present level of the lake. Total elevation = 640 feet above sea level Shoreline was uneven with several inlets, peninsulas

and offshore islands

Glenwood Phase

Some beaches with dunes One of these beach-dune complexes was still present

near Dyer, IN in 1939 Sand ridges on the moraines mark the early shoreline.

Best preserved beaches are along Glenwood-Dyer Road, just east of Glenwood, IL

Largest islands were: Blue Island Mt. Forest Island Glenwood Island Hobart Island in Lake County, IN

Cook County

Glenwood Phase

Blue Island

6 miles long

East side was steep wave-cut cliff

West side had Chicago area’s largest sand deposit

City of Blue Island is at Southern tip

North of Blue Island are Beverly, Morgan Park, Mount Greenwood

Glenwood Phase

During Glenwood Phase, glacier continued to advance and retreat

At one point ice retreated past Straits of Mackinac Happened about 13-13.5 kya; caused lake level to drop Straits were lower than the Chicago Outlet and lake water flowed

out of Mackinac Outlet. Ice advanced again and blocked the Straits so water level

returned and outlet was south again Lake level began to drop slowly as Chicago River eroded its

valley where lake overtopped the moraine 12.2 kya lake level dropped as ice retreated past Straits of

Mackinac again End of Glenwood Phase

Two-Creeks Phase 12.2-11.8 kya Lake level was low

Determined in 1905 when submerged spruce forest just west of the L. Michigan shore near Two Creeks, WI.

Radiocarbon dating showed that the wood was older than the Calumet shoreline

Water level was lower than Calumet Stage 1982 – another submerged forest was discovered near the

town of Pines (sw of Michigan City, IN) Partially decayed spruce trees; many still upright

After 200 years, glacier readvanced and blocked the Straits allowing the water level to rise and flood the forest.

Calumet Phase

11.8 – 11.2 kya Calumet Phase was 35 feet above the present level

of the lake. 20 feet lower than Glenwood level. Total elevation = 620 feet above sea level Much smoother coastline Large number of sand dunes but not as many as

before settlement In some places Calumet Dunes bury part of all of some

Glenwood dunes. Mount Forest Island and Blue Island combined

Washington Heights and Stewart Ridge sand spits formed from the sand that eroded from these islands

Calumet Phase

Ridge Road in Lansing, Munster, and Highland IN is part of Calumet Shoreline Was an offshore peninsula or spit

Calumet and Glenwood beaches were used as high, flat, dry travel routes by Native Americans stagecoaches Now U.S. Highway 6

Calumet Phase

Calumet Phase lasted 600 years 11.2 kya when glacier retreated past the

Straits of Mackinac for the last time Lake level dropped about 28 feet to elevation

of 592 feet above sea level Calumet phase was over

Algonquin Phase

11.2-10.9 kya Beaches can be found farther north along

Lake Michigan few beach deposits of this age at the south end of the lake

2 possible causes Short period - only 300 years Little sand was being transported to southern

shores of the lake

Algonquin Phase

Lake level rose Earth’s crust was rebounding after removal of

ice Lake then eroided the shoreline creating the

steep slope north of Ridge Road in County Algonquin Shoreline is erosional scarp rather

than a beach Algonquin Phase ended by about 10 kya

Chippewa Phase

10.0 – 5.5 kya Extreme drop in lake level

Retreating glacier uncovered a very low outlet for the upper Great Lakes to the Atlantic at North Bay, Ontario

Lake level as low as 381 feet above sea level

Chippewa Phase

Much of the lake plain dried up Maybe 200-350? feet below today’s level

Two deepest parts still had water Area begins about 30 miles north of today’s southern

shore Also a larger basin farther north had water

Chippewa Phase lasted 4000 years, longest of any of the lake phases Throughout this phase, earth’s crust kept rebounding Rebounding slowly raised the level of the North Bay

Outlet, and with it the level of Lakes Huron and Michigan

Forests grew in what is now deep water.

Figure 2. (A) Photo of a submerged spruce stump at the Sanilac site from which the cross-section of sample #1 was cut in July 1999. Approximate diameter of this stump at its base is 60 cm. (B) View across an area of dense forest remains located near the study grid. The larger logs to left of center are c. 3.7 m in length. Depth for both photos = 13 m. Photos by Luke Clyburn.

Chippewa Stage

Great Lakes Huron and Michigan, as they probably looked during the "Stanley Low" period some 8,000 years ago. 

The drowned forest site is now about two miles offshore in 40-50 feet of water.

High Tolleston Shoreline

The Nipissing Phases Began 6- kya Lake Michigan water rose slowly past today’s level About 4.7 kya (603 feet) third major shoreline began

forming at Southern tip of Lake. Shoreline runs through Chicago, calumet City,

Hammond, Gary, Ogden Dunes, Dune Acres, Beverly Shores, and Michigan City

Beach began as a long spt/barrier beach that separated Calumet lagoon from the lake.

3.8 kya lake level began to drop and Calumet Lagoon drained and became the floodplain of what is now the Little Calumet River

High Tolleston Shoreline Tolleston Shoreline Dunes were generally taller than the older and

higher shorelines. Most were removed years ago and the sand was used to raise

ground levels elsewhere High Tolleston Shoreline at 605 feet above sea level

15 feet lower than the Calumet Shoreline 25 feet higher than today’s level Can be seen today east of Michigan Avenue near Roseland in

Chicago (between 100th and 127th Streets). Much of the area is now protected as part of the National Lakeshore

or State Park Cowles Bog, Great Marsh and Dunes Creek

This phase left several prominent landmarks, including the beach ridge that provided the route for Clark Street in Chicago.

Lower Tolleston Shorelines

Outlets of the Great Lakes When the Tolleston Shoreline first formed, the Upper

Great Lakes had three outlets North Bay Outlet near Georgian Bay Port Huron Outlet past Detroit Chicago Outlet

Crustal rebound continued up north, so northernmost North Bay Outlet was raised higher than the two southern outlets – couldn’t carry water out of lakes

Erosion lowered Port Huron Outlet slightly – levels of Lakes Huron and Michigan go down also

Chicago Outlet dried up

Lower Tolleston Shorelines

3.8 kya – Algoma Phase Lake level dropped to current level This happened in a pulsating manner

Lowered water levels resulted from a combination of erosion at Port Huron and dry weather conditions

Higher water levels were caused by periods of greater rainfall

Pulsating pattern produced a series of more than 150 small beach ridges all roughly parallel to the lake and all located north or east of the High Tolleston beach.

Between the ridges were long, low swales that often contained standing water.

These ridges are called the Lower Tolleston Beaches

Lower Tolleston Shorelines

Lower Tolleston Beaches Originally ranged in height from 5 -12 feet and

150 feet in width Most were leveled as SE Chicago, Gary,

Hammond, and East Chicago were developed Can see some in Miller and

Tolleston/Brunswick areas of Gary Gibson Woods has the longest ridges still

remaining

Current Conditions

Current level of Lake Michigan was reached 1500 years ago Currents of the lake bring sand soutward and deposit it at

the southern end of the lake 1500 years ago a sand spit grew south of Stony Island (a

bedrock island in the lakde) Sand spit enclosed a bay creating Lake Calumet 400 years later Wolf Lake formed in a similar manner

Weather patterns cause lake level to fluctuate seasonally May rise more than a foot from late winter low level to a

summer high and then back down again Concerns about global warming and lake levels

The Future

Lake level will most likely drop again Level of Lakes Michigan and Huron is determined by the

level of Lake Eried iinto which they flow Depends on the erosion of Niagara Falls, Lake Erie’s

elevation will remain the same, but as the falls erode away, Lake Erie will drop and so will Lakes Michigan and Huron.

Largest southern sand dunes are in Porter County Indiana Mt. Tom, Mt. Holden Mt. Jackson Mt. Baldy is a migrating dune moves se about 4-6 feet per

year

Reversing the Chicago River

Chicago River flowed into Lake Michigan Carried sewage into the lake which was the

source of Chicago’s drinking water Reversed when canal was dug 1900

Reversing the Chicago River

A solution proposed in 1889 recommended that the Chicago River be reversed.

Instead of flowing into Lake Michigan it would, in effect, flow into the Gulf of Mexico.

The project involved the construction of a 28-mile channel through a glacial moraine and bedrock ridge.

The Sanitary and Ship Canal would connect Lake Michigan at Chicago with the Des Plaines River at Lockport.

It would also be connected to the Chicago River and would be deep enough to permanently reverse the flow of the river.