^CHICAGO and the NORTHSHORE
Jerry A. Lineback
Paul B. DuMontelle
Dorothy C. Brown
with contributions by
Richard A. Davis
University of South Florida
Curtis E. Larsen
University of North Carolina,
Illinois State Geological Survey Guidebook Series 12
GUIDEBOOK SERIES 12
Illinois State Geological Survey
Coastal Geology, Sedimentology,
Chicago and the Northshore
PAUL B. DuMONTELLE
DOROTHY C. BROWN
Illinois State Geological Survey
RICHARD A. DAVIS, Jr.
University of South Florida
CURTIS E. LARSEN
University of North Carolina, Wilmington
prepared for the 4th Annual Field Conference
GREAT LAKES SECTION
SOCIETY OF ECONOMIC PALEONTOLOGISTS AND MINERALOGISTS
September 21 - 22, 1974
TABLE OF CONTENTS
Road log 6
Beach and nearshore sedimentation, western Lake Michigan,
by R. A. Davis, Jr., and W. T. Fox 28
Engineering geology of the Lake Michigan bluffs from
Wilmette to Waukegan, Illinois, by Paul DuMontelle 35
Erosion of till bluffs: Wilmette to Waukegan,
by J. A. Lineback 37
Late Holocene lake levels in southern Lake Michigan,
by C. E. Larsen 46
COASTAL GEOLOGY, SEDIMENTOLOGY, AND MANAGEMENT
CHICAGO AND THE NORTHSHORE
Since 1964, when the water level of Lake Michigan-Huron reached an
all-time record low of 575.86 feet above sea level, the waters of these lakes
have risen through seasonal cycles to a monthly mean level of 580.8 feet in
the summer of 1973 and 580.9 feet in the summer of 1974 (fig. 1). These high
water levels were accompanied by serious storm episodes. In November 1972 and
April 1973, high waves removed thousands of cubic yards of material from the
lake shore; endangered houses, public buildings, and industrial works; and
flooded underground garages, lower floors of high-rise buildings, nearshore
highways, and lowlands. Repairs to sea walls, groins, and sidewalks were
costly; in addition, protective measures using riprap, sand bags, sediment-
filled barrels and tubes, and new concrete and steel structures involved
millions of dollars.
Although earlier shore studies had lapsed in 1962 from lack of funds,
public action was not long in coming. In the spring of 1973, the Winnetka
Conference (sponsored by civic-minded private citizens) emphasized the need for
an emergency conference of local, state, and federal agencies to deal with
shore recession and flooding at Illinois Beach State Park and lands to the
north. The Lake Michigan Federation, based in Chicago, was the moving force
behind the 1973 Lake Michigan Shoreland Conference held at the Field Museum
of Natural History. Almost simultaneously, the City of Chicago's Department
of Development and Planning produced The Lakefront Plan of Chicago , which was
designed to provide shore protection, to create new cultural and recreational
facilities, and to preserve and enhance the beauty of the shore.
Late in 1973, the Illinois House of Representatives established the
special Committee on Lake Michigan, which has held frequent hearings to establish
recommendations for lake and shore management. Shortly thereafter, the mayors
of 14 Northshore municipalities organized the Lake Michigan Shoreline Advisory
Committee for the purpose of coordinating the planning and action of the
The Illinois Department of Conservation and the Department of
Transportation (Division of Waterways) , in cooperation with the Illinois State
Geological Survey and the Northeastern Illinois Planning Commission, began a
study program to produce a comprehensive plan of coastal management for Illinois.
During the spring of 1974, the State of Illinois applied for funds from the
National Oceanic and Atmospheric Administration, Office of Coastal Management.
The Federal Coastal Zone Management Act of 1972 offers federal assistance,
Fig. 1 - Monthly mean levels (feet above sea level) of Lake Michigan-
Huron. (After NOAA, National Ocean Survey, Lake Survey Center,
up to two-thirds of the cost, for the development of state coastal management
programs. In June 1974, the Geological Survey received support from the Illinois
Division of Waterways for the geological study of the shore and nearshore area.
In July 1974, further support was received under the sponsorship of the 1972
Act; the Survey was assigned the task of gathering the physical data necessary
for developing a coastal management program.
Since 1969, the Geological Survey had carried on a modest coastal
study program of the Zion Beach Ridge Complex, a low, ridged, sand plain between
Waukegan and Kenosha. In 1973, upon advice from other agencies, the Survey ex-
tended the study to include the till bluffs south to Evanston. The program
involved the mapping of bottom hydrography and sediment distribution and the
measurement of shore recession rates. With the evolution of a formal state
program, activities have been expanded to include the topographic and hydrographic
mapping of the entire shore and nearshore, the determination of sediment
distribution and littoral sediment drift budgets, the study of the effect of
storm waves and other such phenomena on the distribution of sediments and shore
erosion, the stratigraphy and engineering properties of the shore, the history
of the shore and the estimation of its future, and the collection of a compre-
hensive archive of data related to Lake Michigan and its shore.
The coastal study program has much data to build on. Beginning in
1946, the Illinois Division of Waterways and the U.S. Corps of Engineers
undertook the study of beach erosion on the Illinois shore. Subsequently,
the Division of Waterways made observations of lake levels, wave heights,
refraction, and periods of wind duration and velocity. In addition, surveys
were made of nearshore, shoreline, beach, and bottom sediments. The aerial
photographs that were taken of the shore between Evanston and the Wisconsin line
have been especially useful. Unfortunately, nearly all such studies ended in
1962 when funds were no longer available. Consequently, 10 years of records
that would have included the record low-water level of the lake and the spec-
tacular 1964 to 1974 rise in lake level were never made. It is hoped that the
present programs will codify and assure a continuous study and management
program for the future.
Geologically, the entire shore of Lake Michigan in Illinois is very
young. It is generally underlain by the Wadsworth Till Member of the Wedron
Formation of Woodfordian age (about 13,000 radiocarbon years B.P.). The Wads-
worth, in turn, lies on bedrock dolomite of Niagaran (middle Silurian) age.
The Wadsworth is the material of the Zion City Moraine, which forms the 50-foot
bluffs at Waukegan, and of the Highland Park Moraine, which forms the 55- to
75-foot bluffs between Winnetka and Lake Forest. South of Winnetka, the shore
is covered by shallow-water, nearshore lake sediments in the form of stranded
beaches, bars, spits, and deltas that were deposited in ancestral Lake Chicago
during the Glenwood (640 ft elev.), Calumet (620 ft elev.), Toleston (605 ft
elev.), Nipissing (600 ft elev.), and Algoma (595 ft elev.) lake stages (fig. 2)
In a few areas , such as those near the mouths of the Chicago and the Calumet
Rivers and in the vicinity of Loyola Park on the far north side of Chicago,
laminated silts deposited in still waters (Carmi Member of the Equality
Formation) have been recorded. Where these ancient lake sediments are found,
the shore is not far above lake level. Most of the shore is between 585 and
590 feet in elevation, well within reach of storm surges and severe seiches
during high lake levels.
North of Waukegan, the shore is fronted by the Zion Beach Ridge
Complex described by Hester and Fraser (1973) and Fraser and Hester (1974).
The complex, which is the main subject of much of the field trip, is a low
sand plain, little more than a mile wide, which extends from Waukegan to
Kenosha some 14 miles to the north. The area is very young, about 3500 years
old at the north end and still being actively deposited today at the south end.
Virtually all features seen in the area will be of latest Wisconsinan or of
We are indebted to many people. Charlene Anchor drafted most of the
illustrations and typed part of the text in addition to doing field work for
the project. Mary Collinson typed part of the. text. Mildred Newhouse typed
the manuscript and coordinated the project. Phyllis Picklesimer typed the
final version. Richard Olson piloted the plane from which most of the aerial
photos were made. Kip Mecum, Richard Berg, and Rod Norby did much of the
Fig. 2 - Map of lakeshore to be observed from M. V. TRINIDAD. Map taken
from USGS Chicago Loop and Evanston Quadrangles (7h minute, re-
field work and performed many other duties. Karen Mecum, Robbie Berg, and
Katherine Olson helped with field trip arrangements.
Ranger Robert Needham of Illinois Beach State Park and Department of
Conservation District Land Manager John Comerio have been helpful in many ways,
The Village of Lake Bluff and the Lake Bluff Park District have freely given
access to their lands along the shore and greatly expedited our studies. We
are also grateful to the Johns-Manville Products Corporation and their
Community Relations Representative, Roy F. Winkworth, for their consideration.
In addition, we thank George Travers of Commonwealth-Edison Company for up-
to-date information concerning the Zion Nuclear Generation Station.
CHICAGO RIVER TO NORTHSHORE AND RETURN
ABOARD THE M.V. TRINIDAD
SATURDAY, SEPTEMBER 21, 1974
LEADERS: Charles Collinson, Jerry A. Lineback, Paul B. DuMontelle, Curtis E.
Larsen, Dorothy C. Brown
MEETING PLACE: south side of Chicago River, Wacker Drive at La Salle, across
the river from and two blocks west of Marina City (fig. 3). The M. V. TRINIDAD
will leave the dock at 10 a.m. Parking is available in the general area of the
dock. Some free parking can be found on the lower level below Wacker Drive
(South Water Street) opposite the TRINIDAD' s dock. A city parking building is
located on the north side of the river on La Salle Street, and private lots are
located on the south side of Wacker Drive between Clark and Wabash. Other lots
are available under Michigan Boulevard on the north side of the river. The
TRINIDAD's dock may be reached from 1-94 exit on Ohio Street — take Ohio to
La Salle, turn right, and proceed seven blocks to Wacker, which borders the
Chicago River. The dock can also be reached from Lake Shore Drive (U.S. Route 41)
via Jackson, Monroe, or Randolph Streets by going westward to La Salle, then
north to Wacker.
At 10 a.m. , the TRINIDAD will sail on the Chicago River past Marina
City, the Sun-Times Building, the Wrigley Building, and the Tribune Tower —
all on the north bank. After the TRINIDAD passes under Michigan Boulevard,
the white Standard Oil Company Building can be seen due south. The Sears Building,
the tallest building in the world, is west of the Loop and can best be seen
from the lake. The John Hancock Building, which dominated the skyline for a
few years, is located nearly a mile due north. The Chicago River formerly
flowed eastward directly into the lake (fig. 2), but in the 1860s the Illinois
and Michigan Canal was dredged, and locks were built at the mouth of the river
to divert the flow westward and carry away the sewage of the city.
The Chicago lakefront has been the city's pride for over 100 years and
the city is now committed to the long-term "Lakefront Plan of Chicago," wherein
the shore will be developed as a multi-use archipelago of artificial islands
built from more than 67 million cubic yards of stone to be taken from underground
development programs — the expansion of the subway and the Metropolitan Sanitary
District's "Project Underflow" tunnels. The plan is a reaffirmation and
enhancement of the Daniel Burnham plan of 1909, which called for "beaches,
lagoons, islands, harbors, and cultural facilities." The Lakefront Plan of 1973
calls for 1055 to 1390 new acres of islands and shore, 10 miles of new beaches,
9 new launching ramps, spaces for 5000 boats, a stable, and 6000 acres of pro-
tected waters. Displays detailing the plan are available aboard the TRINIDAD.
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After leaving the locks, the TRINIDAD will traverse the Outer Harbor
where the spectacular Chicago skyline can be seen to its fullest advantage.
Northward toward the "Gold Coast" are sites where high water and storm-driven
waves have posed serious physical and legal problems. Some arise from wave
concentration due to reflection. We shall pass Oak Street Beach, North Avenue
Beach, Montrose-Wilson Beach, and others — all of which have their own character-
istics. We shall pass Calvary Cemetery, where Sheridan Road is involved in a
contest with the lake, and we shall examine the Northwestern University landfill,
which may or may not interrupt the southward flow of littoral sand. Farther
north, beyond Wilmette, we shall encounter the bluffs of the Northshore and
discuss both erosion and governmental problems involved with managing the bluffs
and restoring the beaches.
Sack lunches will be served at noon. For those who skipped breakfast,
coffee and doughnuts will be available aboard.
The general geology of the lake's southern basin, the lake circulation
patterns, and the sediment distribution in the basin will be discussed on the
return trip. After returning to the dock in early afternoon, please take personal
transportation to Illinois Beach State Park at Zion, the field trip headquarters,
45 miles to the north. Suggested routes give a choice between rapid travel and
Upon arrival at Illinois Beach State Park Lodge in late afternoon,
several beach displays will be available, as well as demonstrations of the park's
Littoral Environment Observation (LEO) Station. Those who wish may hike southward
into the Nature Preserve part of the park — the last natural shore in the State
of Illinois — where one of the few examples of high-water beach accretion can be
observed. If possible, boats and cars will be available for transport into the
preserve. If waves are high, the Survey storm-wave sled will be demonstrated.
SATURDAY EVENING — Happy Hour, Banquet, Business Meeting, and Lectures on Lake
Michigan Shore Studies.
ILLINOIS BEACH STATE PARK
TO LAKE BLUFF AND RETURN
SUNDAY, SEPTEMBER 22, 1974
LEADERS: Charles Collinson, Jerry A. Lineback, Paul B. DuMontelle, Curtis E.
Larsen, Dorothy C. Brown, and Leon R. Follmer.
Meet in parking lot at Main Beach 3/4 mile north of Illinois Beach
Lodge. Cars may be left in the parking lot. STOP 1 will be near the parking
lot so late arrivals may join the group there. See figures 4A-D for route maps
QTQD MQ i\ ILLINOIS BEACH STATE PARK, MAIN BEACH. Eh SE% Sec. 27,
T. 46 N. , R. 12 E., Zion Quadrangle.
The main bathhouse on this beach, Illinois Beach Lodge, and the
three bathhouses to the north were the subject of a hastily convened conference
in April 1973. High water and strong winds from the northeast had removed
hundreds of cubic yards of sand in a matter of hours from what were already
seriously eroded beaches (table 1 and fig. 5). The service road was cut and
much of the park was flooded including the lower levels of the Lodge, the
roadways, and the parking lots.
The first serious erosion due to the present high water cycle occurred
at the north end of the park, just south of the Zion Nuclear Generation Station
site, not long after a safe harbor jetty was built for construction purposes.
As first damage occurred, the reactor builders responded with the construction
of a steel bulkhead and the placement of riprap as well as sand fill. At first,
the materials were placed only at the site of erosion but, as that portion of
the shore was armored, erosion moved downdrift (southward). Consequently, riprap
now extends as far as this main beach (pi. 1). As the material was eroded by
storms, sediment moved down the shore as slugs of material manifested by migratory
prominences. Plate 1 shows the main beach and bathhouse in 1971 and 1973, after
two severe seasons of storms. In winter 1974, the 30-year old flagpole was
undermined along with the main bathhouse which was subsequently removed. Recently,
the beach was refurbished by the addition of 25,000 cubic yards of sand to cover
debris and to provide resources for the coming winter months . If the beach is
further cut away by severe storms, the material will supply littoral drift
sediment southward (downdrift) where the Lodge, the one structure the park cannot
afford to lose, is located.
The sand dike at the back of the beaches is to reduce flooding due to
wave run-up which measures seven to eight feet in height in this area.
Figs. 4A to D - Field conference route maps showing numbered stops. The
maps are modified from USGS Zion and Waukegan Quad-
rangles (7% minutes, revised 1972).
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A. Emergency riprap groins and sand fill near northern bath-
houses in Illinois Beach State Park in October 1971. Later,
higher water levels and storms required further additions
of riprap and fill.
B. Shore erosion north of southernmost concrete bathhouse
(No. 3) showing advance of erosion in front of advancing
riprap wall in background. In April 1973, 140 feet of
recession occurred at this place during a single storm
C. Houses located just north of the Zion Nuclear Generation Station,
In 1972 these were protected by a hundred feet of grassy lawns,
trees, and patios. This picture was taken in July 1973. In
1974, they were entirely undermined and subsequently demolished.
D. House located on Lakefront Drive in Zion. The house was
protected by many cubic yards of concrete but was outflanked
by waves running up as much as 8 feet above lake level in
E. The main beach at Illinois Beach State Park in October 1971.
The beach was especially wide because of the addition of
material eroded by drift in the northern part of the park.
F. The main beach at Illinois Beach State Park in January 1974.
Almost 150 feet of recession had occurred since 1971. The
rocks and posts in the left foreground mark the 1951-53 high
water levels and were covered and forgotten for 20 years.
The flag pole and main bathhouse were undermined during spring
00.00 00.00 Leave Main Beach Parking Lot. Turn west on entrance road
past trailer camping area and cattail marsh. In the marsh
to the right, cores containing peat were dated at 715 ± 75
radiocarbon years B.P. and 540 ± 75 radiocarbon years B.P.
Eventually, such dates will permit the reconstruction of a
precisely detailed history of the sand plain.
00.95 00.95 Chicago and Northwestern R.R. tracks.
01.10 02.05 STOP LIGHT. Intersection of Wadsworth and Sheridan Roads.
Turn right (north) into Zion.
01.45 03.50 STOP LIGHT. Zion is a town with a religious heritage. It
is experiencing substantial growth at present partly due to
the location of the Zion Nuclear Generation Station here.
01.95 05.45 STOP LIGHT. Cemetery on right.
02.20 07.65 STOP LIGHT. This is the main business district. Although
small, Zion prides itself on handsome parks, a modern library,
swimming pools, and an ice rink. The town was founded in
1900 by a religious group led by the Reverend John Alexander
Dowie. Rev. Dowie was the founder of the Christian Catholic
Church (a Protestant sect) which surveyed and planned the
entire town of 6400 acres before a single building was built.
The large, block-long Zion Hotel (originally named the
Elija Hospice) on the right was built in 1901 for housing
the workmen who came to build the town. Later it was used
to house the faithful who made pilgrimages here. It has
300 rooms with dining facilities for 1000. The large red
brick houses along Shiloh Boulevard were built for the
leaders of the sect. Street names like "Galilee," "Emmaus,"
and "Ezekiel" clearly show the town's heritage. The Zion
Passion Play, still performed regularly during summer months,
draws visitors from great distances.
02.43 10.08 STOP LIGHT. Intersection of Shiloh Road and Sheridan
Boulevard. Turn right and proceed eastward. The land ahead
is a natural marsh and bog area which is commonly flooded
by heavy rain and by storm surges from the lake.
02.80 12.88 R.R. tracks and power lines on left.
03.50 16.38 R.R. tracks. Continue eastward; STOP NO. 2.
STOP NO. 2>
NORTH SIDE ZION NUCLEAR GENERATION STATION. SW^ NE^
Sec. 23, T. 46 N. , R. 12 E. , Lake County, Zion Quadrangle.
The Zion Nuclear Generation Station (pi. 2) was essentially completed
in 1973 by Westinghouse for the Commonwealth Edison Company. The plant, a twin
reactor of the boiling water type with a capacity of 2200 Megawatts, is the
largest nuclear generation station in the world. At full capacity, it
circulates one billion gallons of cooling water from the lake every 24 hours.
Water is taken in through a 2600-foot tunnel buried in the floor of the lake.
Two outlets 765 feet apart and 765 feet from the crib house float the heated
water out onto the top of the lake water. The excurrent water must be no more
than 19.6°F above ambient water temperature. The heated water at each outlet
covers 1^ acres at lake bottom and covers 54 acres at the 3°F isobar. Water
is at ambient temperature 2000 yards downdrift.
Sediment distribution at the reactor site is being carefully mapped
by the Illinois State Geological Survey. The possibility is being considered
that heated currents may to some extent affect longshore littoral sediment
drift and possibly divert some sand lakeward beyond wave base.
The shore north of the reactor (updrift and essentially unaffected
by the reactor) was the site of severe erosion and much damage to dozens of
residences, streets, and highways during fall and spring storms of 1972-73
(pi. 3). Many residents were originally displaced by the nuclear plant and
were greatly discouraged when high water drove them from new home sites .
Numerous washover deltas attest to the severity of the 1973 storms. The State
of Illinois is now acquiring the land for addition to Illinois Beach State Park
and has forbidden the construction of permanent buildings in the shore zone.
16.38 Leave STOP NO. 2 and return westward to Sheridan Road.
09.82 26.20 STOP LIGHT. Shiloh Boulevard and Sheridan Road. Turn
left (south) , returning past the intersection of Wadsworth
Road and Sheridan Road. Note the absence of liquor stores
in Zion proper.
08.03 34.23 STOP LIGHT. Wadsworth Road. Turn left (east) to STOP SIGN
at main beach parking lot in Illinois Beach State Park.
01.90 36.13 STOP SIGN at main beach. Turn right on Beach Lodge Road.
00.40 36.53 Lodge on left.
00.10 36.63 Turn left toward Nature Area and continue straight ahead
through parking lot to gate.
00.10 36.73 Enter gate to Nature Preserve. This area is reserved for
hiking. Groups must have special permission to enter.
During summer the Park Naturalist conducts nature hikes on
a daily basis.
00.95 37.68 Follow gravel road through Nature Preserve curving around
to the left until road turns north. Buses will turn around
here. Walk east to lake shore through break in ridges.
Then turn south to mouth of Dead River.
A. Aerial view of the Zion Beach Ridge Complex as developed in
Illinois Beach State Park. The bluff line shows in the
lower left. Dead River begins in the upper left and meanders
to the upper center. The light line paralleling the shore is
the submarine nearshore bar. Illinois Beach Lodge is in the
extreme upper left.
B. Inflatable runabout equipped with recording fathometer and
short-wave radio. The boat is extremely stable, safe, fast,
and portable. It is used for nearshore hydrographic surveying,
C. View lakeward at south end of beach at Illinois Beach State
Park. Shore advance is in progress here by means of the
building of washover fans and deltas such as the sand and
gravel structure in the near background. Windblown sand
and silt helps to build the structures into ridges by en-
trapment around beach grasses.
D. Jetty of the Outer Harbor at Waukegan showing the public
beach in the background. The light area of water in the
right foreground represents suspended fine sediment. The
dark area between it and the jetty consists of pollutants
from the shore.
E. Scene near the entrance lock to the Chicago River. A high-
rise residential building on the left is well protected from
waves by the harbor jetties. The John Hancock building is
on the right. The freighter is docked at Navy Pier.
F. 2200 Megawatt nuclear generation station at Zion. The sedi-
ment lining the shore in front of the station is littoral
drift material in transit past the station.
A. Severe bluff erosion at Lake Bluff where a sheet piling bulk-
head has been left unrepaired. The loss probably represents
only 4 years of recession.
B. Wave reflection on the updrift side keeps the groin scoured
clean while some sediment remains on the downdrift side.
C. Wedron Till Member, STOP NO. 6, just south of the Lake Bluff
Sewage Plant. Note lines of seepage along the top of the
D. Undercutting of an exposed till bluff causes slumping and
rapid transport of the slumped material.
E. Partly-submerged short groins (top) and long, emergent
groins give little protection at high water as evidenced
by the light-colored patches of water which mark lakeward
currents induced by reflected waves.
STOP NO. 3>
MOUTH OF DEAD RIVER, ILLINOIS BEACH STATE PARK. NE^ SE^
NE% Sec. 3, T. 45 N. , R. 13 E. , Lake County, Zion Quadrangle.
This is a middle location on the last stretch on natural shore left
in Illinois — 2 miles of Illinois Beach Nature Preserve. Unfortunately, recent
storms accompanied by the 1970-74 high water levels have depleted the lakeward
tiers of highest dune-ridges. The area is especially valuable to sediment-
ologists as well as botanists and zoologists because it not only preserves
natural beach features, but it also traces the history of the shore ridge-by-
ridge. As can be seen from figure 14 in the report by Curt Larsen (p. 50), the
ridges we stand on date from the 1800s and earlier, while those southward date
up to modern times .
The rush, cattail, and grass marshes that are well developed between
the ridges are old enough to have developed peaty zones that are datable by
radiocarbon methods. These radiocarbon dates give us an opportunity to interpret
past history and to predict the future for the area. The study by R. A. Davis
and W. T. Fox (this Guidebook) of the beach, wind, wave, and current area lying
just to the north was not very successful because the weather in summer 1974
was exceedingly mild.
Exposed along the beach is a widespread dark paleosol horizon that
resembles a heavy mineral concentration. It is essentially modern.
37.68 Leave STOP NO. 3 and return to Beach Road.
00.95 38.63 Junction with Beach Road. Turn left (southwest) and
travel to Sheridan Road. We are passing through bogs,
estimated by means of radiocarbon dates and archeological
remains, to be between 300 and 700 years old.
01.10 39.73 STOP SIGN. Intersection of Beach Road and Sheridan Road.
Turn left (south) .
00.70 40.43 Yorkhouse Road. Continue ahead. We enter Waukegan
(pop. 65,200) at Blanchard Road. Established as a trading
post in 1695 and incorporated as the town of "Little Fort"
in 1841, the name was changed to the Indian name "Waukegan"
in 1859. Waukegan is the Lake County seat — Lake being
Illinois' second wealthiest county — and a long-time manu-
facturing center. Johnson Outboard Motors and Outboard
Marine Corporation, manufacturers of inboard/outboard boat
motors and Lawn Boy mowers, are located at the waterfront,
along with U.S. Gypsum Company. Larsen Marine, also lo-
cated there, is a well known outfitter of yachts. U.S. Steel
has a large wire plant on the south waterfront. Johns-
Manville, manufacturer of insulation and pipe products, has
been located at the same site for decades.
01.20 41.63 STOP LIGHT. Seventh Street. Continue southward.
00.65 42.28 STOP LIGHT. Greenwood Avenue. Turn left proceeding
eastward, downhill, toward the lake. Bowen Park is on
00.46 42.74 STOP SIGN. Turn left (north).
00.15 42.89 STOP SIGN. Continue north, entering Johns-Manville
manufacturing plant. Proceed to northernmost side of
building and turn right (east) toward the lake. Follow
plant road past spoil piles to end.
STOP NO. 4>
SOUTH BEACH, ILLINOIS BEACH NATURE PRESERVE. West edge,
SW%, Sec. 11, T. 45 N. , R. 12 E. , Lake County, Zion
The 2^-mile stretch of shore north of the Waukegan Power Station
pier is the only significant part of the Illinois shore that is advancing
toward the lake. More than 50,000 cubic yards have been added since 1970.
The rate is related to storm episodes that remove material to the north and
move it southward. Most material that travels as far south as the pier is
shunted lakeward by the excurrent cooling water of the power plant.
The area illustrates the process by which the beach ridges and
dunes grow. High water levels and storm surges cause numerous washover
deltas by which sediment deposits up to a few feet deep are left perched above
water level. Then, as seasonal winter low water levels occur or as the water
level in general falls, very wide beaches of fine sand are exposed to winter
onshore winds. Then sand is piled onto the upper beach where it is trapped
by vegetation and built into a dune-covered beach ridge. If the water levels
were again to fall to the record low level of 1964, a beach several hundred
feet wide would be exposed along this shore at this location.
42.89 Leave STOP NO. 4 and return to Main Gate.
01.30 44.19 Main Gate. Turn left (south) over overpass on blacktop
road paralleling the Chicago & Northwestern R.R. tracks.
00.15 44.34 STOP SIGN at top of overpass. Continue straight ahead.
00.15 44.49 Entrance road to Commonwealth-Edison Waukegan Fossil Fuel
Generating Plant on left. Alternate STOP NO. 4A is at the
lakeward end of this road.
Jenkins-Boiler plant entrance on left.
Johnson Motors Marine Service School Plant No. 3 on left.
STOP SIGN at top of overpass — junction with Mathon Boulevard
Proceed straight ahead. The U.S. Gypsum Company dock can
be seen to the left.
00.10 45.03 Four-hundred-foot bulk carriers dock here. STOP SIGN.
Turn left (east). Large ship's propellor on corner near
Mathon's Restaurant which specializes in fine fish.
00.10 45.13 Turn right into parking spaces opposite the Waukegan Yacht
Club for STOP NO. 5. Coffee and harbor gawking.
STOP NO. 5>
ATKINSON'S BOATHOUSE, WAUKEGAN HARBOR. SW^ NW^ Sec. 22,
T. 45 N., R. 12 E. , Lake County, Waukegan Quadrangle.
Coffee and doughnuts in the park.
Waukegan Harbor is the only public harbor between Wilmette, 20 miles
to the south, and Kenosha, 15 miles to the north. The harbor dates from the
turn of the century and in recent years has become severely crowded.
The harbor jetties are important sedimentologically , as well as from
a coastal management point of view, inasmuch as southward migrating littoral
sediments are trapped and/or diverted lakeward by the jetties so that the harbor
mouth must be dredged periodically to maintain navigation depths. Approximately
70,000 cubic yards of sand were dredged during summer 1974 and stockpiled near
the Johnson Outboard Motors plant. Such dredgings are very useful in estimating
annual sediment budgets.
Apparently little sediment bypasses the Waukegan area as manifested by
the paucity of sandy sediments on the nearshore lake floor for some distance
south of Waukegan.
The shore between the Waukegan Power Plant pier and Waukegan Harbor
is relatively stable with enough sediment bypassing the power plant pier to
maintain broad low-slope beaches and nearshore shallows. At the same time,
the Waukegan Outer Harbor jetty effectively retains the material.
The harbor has a long history as a commercial fishing port and, although
the industry in essence died out for a period of nearly 30 years, the demise of
the lamprey and the advent of salmonid and trout stocking have revived commercial
fishing and given rise to a flourishing sport fishing industry as well.
45.13 Leave STOP NO. 5 going south on Harbor Place Road.
00.08 45.21 STOP SIGN. Turn right (west). Ramps for trailered boats
lie directly ahead. The recent advent of salmon and lake
trout fishing leads to great congestion at times. In
addition, fleets of sailboats have been added in recent
00.02 45.23 STOP SIGN. Turn left (south) paralleling R.R. tracks, up
00.45 45.68 STOP SIGN. Intersection with Belvidere Street. Turn right
(west) for one short block.
00.05 45.73 STOP LIGHT at intersection of Sheridan Road and Belvidere.
Turn left (south) .
00.28 46.01 STOP SIGN. Turn half left. Sheridan Road becomes Genesee
Road. Continue ahead.
STOP LIGHT at South Street. Continue ahead.
STOP LIGHT at 11th Street. Continue ahead.
STOP LIGHT. Abbott Laboratories on the left.
STOP LIGHT. Continue ahead to 22nd Street.
STOP SIGN. 22nd Street. Turn left (southeast) over R.R.
00.03 48.26 Turn right (south) after crossing tracks. Road is once
again Sheridan Road. North entrance to Great Lakes Naval
00.50 48.76 STOP LIGHT. Main gate to Great Lakes Naval Training Center,
Proceed south on Sheridan Road.
00.40 49.16 FLASHING YELLOW LIGHT. Naval hospital on left. Entering
Lake Bluff (pop. 5000).
01.85 51.01 Scranton Avenue in Lake Bluff. Turn left (east) into
Village of Lake Bluff and continue eastward on Scranton
00.83 51.84 Street ends at Lake Park. Turn right, then down bluff road
through gate to sewage disposal plant.
00.15 51.99 Turn around in parking lot.
^ FIGURE 6. ERODING TILL BLUFF JUST SOUTH OF THE SEWAGE
STOP NO. 6^ TREATMENT PLANT AT LAKE BLUFF, ILLINOIS. SE^ NE% Sec. 21,
T. 44 N. , R. 12 E. , Lake County, Waukegan Quadrangle.
This exposure is a typical example of an actively eroding till bluff.
The absence of a protective beach allows waves to strike with full force on
the toe of the slope. This exposure is actively' slumping and the slump material
commonly covers the lower slope. Dead trees on the beach attest to the amount
of material removed.
Gray si It and soi I
. Gray/1 ight buff
Gray/buff, fine/medium .2
0. cross-bedded sand <£
7ti-.li;.;Ji.]\L_.^g. silt with sand lenses
8. Light brown, medium
Thi nly bedded si It
Clay with gravel at base
Gray, si Ity, clay ti I
with few pebbles and
some lenses of sandy
Light brown sand
7. Gray to buff conglomerate;
contains pebbles of clayey
silt in sand matrix; grades
laterally into sand northward
_and into contorted silt southward
6. Light brown, coarse, cross-bedded
sand; contains pebbles; is gray or
oxidized red and cemented in places
"Cobble and boulder bed with irregular
Gray, si Ity, clay ti I I with few
pebbles; blocky and massive
3. Gray, faintly bedded silt with
lenses of si Ity clay
2. Gray, si Ity, clay ti I I ; blocky
with few pebbles
Gravel and cobble beach
Fig. 6 - Stratigraphic section just south of Lake Bluff sewage disposal
plant. S& NEk, Sec. 21, T. 44 N. , R. 12 E. , Lake County,
This bluff exposes three glacial till units and intercalated sand
deposits belonging to the Wadsworth Till Member of the Wedron Formation. These
tills are similar in mineralogy and grain size and are associated with various
moraines of the Valparaiso and Lake Border Systems. The Wadsworth Till Member
is the youngest glacial till exposed in Illinois , having been deposited about
13,500 radiocarbon years B.P. Characteristic mineralogy and grain size data
for tills in the bluffs along Lake Michigan are given by Lineback later in
The lower two tills (units 2 and 4) are separated by a bed of silt
(unit 3) and make up about two-thirds of the bluff. There is a boulder bed
(unit 5) at the top of the second till. About 3 meters (10 ft) of cross-bedded sand
(unit 6) overlies the till. Above the sand is a bed composed of silty clay
and rock pebbles in a sand matrix. This unit (7) grades northward within the
outcrop into sand and southward into contorted silt. All units above the
boulder bed are laterally gradational and badly slumped. Units 8 to 12 are
exposed at the top of the northern part of the exposure. Units 8A through
11A are exposed in the central part of this bluff segmant.
The upper till (unit 9A) is similar to the lower tills, but with
slightly more silt and less sand. This till may be related to the Highland
Park Moraine, the crest of which is 1.5 kilometers (0.9 mi) west of this site.
Lying on the top of the till is 1 to 1.5 meters (3 to 5 ft) of thinly bedded
silt, sand, and clay (unit 10A) . A thin gravel bed separates this unit from
the till. Clay beds in this unit may contain varves. Unit 10A is believed
to be nearshore lacustrine sediments deposited during one of the highest lake
levels of glacial Lake Chicago. This probably correlates with the Glenwood
stage that here lies at about 200 meters (650 ft) above mean sea level.
Unit 10A is therefore assigned to the Equality Formation. The Modern Soil
(unit 11A) is developed in these lacustrine deposits.
A bore-hole located near the park entrance a block north of the
exposure penetrated 6.0 meters (20 ft) of lacustrine silt and sand before
reaching the till.
Factors encouraging erosion here include: (1) no protective beach
or man-made structures to prevent the waves from striking the bluff, (2)
materials that will quickly slump when the slope is overs teepened, (3) the
removal of protective vegetative cover by earlier erosion, and (4) the presence
of ground-water seeps that keep the material wet and prone to slump. Recession
here is estimated to be at least 2 meters (7 ft) along the crest of the bluff
since August 1973. Winter storms during 1974-75 are expected to result in
continued removal of material from the bluff. The gravel beach indicates
that fine material is quickly removed by wave action and currents.
BEACH AND NEARSHORE SEDIMENTATION
WESTERN LAKE MICHIGAN
Richard A. Davis, Jr., Department of Geology,
University of South Florida, Tampa, FL 33620
William T. Fox, Department of Geology,
Williams College, Williamstown, MA 01267
Two time-series studies of the process-response mechanisms operating
in the beach and inner nearshore areas of western Lake Michigan were conducted
by the authors as part of a long-term field project (Fox and Davis, 1973a).
The ultimate objective of this project is the quantitative prediction of coastal
changes utilizing computer modeling techniques. The study areas at Sheboygan,
Wisconsin (1972) and Zion, Illinois (1974) (fig. 7) which represent the only
large stretches of sand beach on the western coast of Lake Michigan, were
occupied for 30 and 15 days respectively during the summer. Such studies in-
cluded frequent observations of environmental parameters and daily surveys of
the beach and adjacent inner nearshore zone.
Among the environmental parameters measured were barometric pressure,
wind speed and direction, wave period, breaker height and angle of approach,
and longshore current velocity. Detailed topographic maps were prepared from
daily surveys of a small portion of the coast; 1600 feet at Sheboygan and 800
feet at Zion. Comparison of daily maps by computer permits quantitative analysis
of the changes in the beach and adjacent nearshore areas. Erosion and deposition
data may be related to environmental variables, thus providing the framework
for preliminary or conceptual models. These models are then formulated into
quantitative simulation models which may have prediction capabilities. To date,
such a simulation model has been developed .for the eastern coast of Lake Michigan
(Fox and Davis, 1973b) with gratifying results.
The western coast of Lake Michigan has few stretches of well-developed
sand beaches. There is a significant amount of gravel present on the beach and
adjacent nearshore zone in both study areas. Gravel was the dominant beach
sediment at Zion, Illinois, during the summer of 1974. Low coastal dunes
1 Supported through Geography Branch, Office of Naval Research, Contract #388-092,
J >• Ludington ^
Sheboygan J /
I 1972 /
1 \^# Muskegon
\ LAKE .970*
] MICHIGAN ^Holland
Wl. 1 J
ILL. J 1974 1974 #
\ A St. Joseph
\ 1969 m
CHICAGO Uyi Xmi ^m^A
V/X S Ml. ^Hi Study area
i^\ ^^ IND. 15 Mi
I 1 — 1 1 1 1
ILL. 1 IND.
Fig. 7 - Index map showing location of study areas.
landward of the beach serve as a primary source of sediment for the beaches in
both areas. The shoreline is slightly sinuous at both sites with the greater
amplitude at Sheboygan. Late spring and early summer beach accretion were
evident at both sites in the form of welded ridges of sediment and rather wide
beaches, considering the recent lake level rises.
A marked difference existed between the longshore sand bars in the
two areas. At Sheboygan there were two bars, one at a distance of about 100
feet from shore with its crest at a depth of 3.5 to 4.0 feet and another more
continuous bar at a distance of 350 to 400 feet with its crest 6 feet deep.
A single, continuous bar was present at Zion. It was about 300 feet from shore
with its crest at a depth of 7 to 8 feet.
The slope of the inner nearshore was steeper at Zion. This, coupled
with the absence of a shallow nearshore sand bar (fig. 8), caused some signifi-
cant differences in the monitored variables at the two sites. The steep and
effectively nonbarred configuration at Zion is an important factor in the recent
erosion rates and will be discussed in more detail below.
Any consideration of coastal sedimentation must include an analysis
of the weather systems which affect the study areas and their relationships
to coastal processes. Western Lake Michigan is in the belt of prevailing
westerly winds and features cyclonic low pressure systems as the dominating
energy-generating mechanism. During the summer months when field studies are
conducted, these cyclones move in a west-to-east direction and pass across the
Great Lakes area. Prevailing winds are from the south and southwest (fig. 9).
As the low pressure system approaches the west coast of Lake Michigan,
winds are from the southwest to south-southeast along the beach. After the
center of the cyclone passes over the west coast, there is a reversal of wind
direction to the north. It is at this time that wind speed is generally quite
high and large waves are generated.
Previous studies both on Lake Michigan and on marine coasts have
demonstrated that fluctuations in barometric pressure are of prime importance
in the generation of coastal processes and in the eventual morphologic re-
sponses. The periodic passage of cyclonic systems and the accompanying fall
and rise in barometric pressure cause winds to change speed and direction.
These in turn change the wave size and direction of wave approach. The waves
themselves, coupled with the longshore currents which they generate, bring
about significant changes to the beach and inner nearshore zone.
Fig. 8 - Beach and nearshore profiles at Sheboygan (above) and Zion
Fig. 9 - Wind direction and duration in hours- for Sheboygan and Zion.
A generalized or conceptual model of western Lake Michigan coastal
processes has been developed from detailed environmental data (fig. 10). As
barometric pressure falls, winds from the south increase in speed causing an
increase in breaker height and a swift, northerly flowing longshore current.
Peak energy conditions occur just after the minimum barometric pressure values
as the curve rises steeply (fig. 10). A reversal in wind direction occurs
during the rise in barometric pressure and causes the direction of wave approach
and longshore current to reverse also. This occurs as the energy level decreases,
The steep nearshore slope on the west coast of Lake Michigan coupled
with a general absence of shallow sand bars permits waves to approach the shore
with little refraction. As a result, longshore currents are not prominent
except during storm conditions and then they are present only quite close to
the shore. The net result is that the rate for coastal processes on the west
coast of Lake Michigan is less than that on the east side. Sediment transport
rates in the littoral zone would be expected to be correspondingly lower.
Because of the generally low energy conditions that prevailed during
both periods of study, no large-scale morphologic changes were recorded. The
steep slope and relatively deep bars dictate that the most marked changes occur
on the foreshore beach. High energy periods at both study areas caused the
same general changes with an increase in the amplitude of the shoreline sinuosity.
During subsequent periods of low energy, the shoreline was somewhat straightened
with protuberances eroded slightly and accretion occurring in the embayments.
The above morphologic changes, which reflect the prevailing conditions,
do not take into account the severe winter storms. Such phenomena are respon-
sible for the vast majority of the coastal changes, especially the rapid retreat
of the shoreline during the past few years. It is critical to understand that
nearly all erosion takes place during only a few storms per year.
Coastal processes along western Lake Michigan respond directly to low
pressure systems that move in a generally west to east direction. Changes in
the coastal processes, especially breaker height and direction of approach, and
longshore current velocity and direction, are predictable, at least semi-quan-
The steep nearshore slope and the position of longshore sand bars
along western Lake Michigan permit waves to approach the shore with little or
no effect from the bottom. Therefore, wave energy at the water's edge is quite
high. In addition, the depth of water causes little refraction until the waves
are only a few feet from shore. This results in a narrow, effective, longshore
Fig. 10 - Diagram illustrating relationship between barometric pressure,
breaker height, and longshore current direction for Zion beach
current for transporting sediment. Consequently, there is less lateral sedi-
ment transport with respect to onshore-offshore transport than on a coast with
a less steeply inclined nearshore such as in eastern Lake Michigan.
Fox, W. T., and R. A. Davis, 1973a, Coastal processes and beach dynamics at
Sheboygan, Wisconsin, July 1972: O.N.R. Technical Report No. 10,
Contract 388-092, 94 p.
Fox, W. T., and R. A. Davis, 1973b, Simulation model for storm cycles and
beach erosion on Lake Michigan: Geological Society of America
Bulletin, v. 84, p. 1769-1790.
ENGINEERING GEOLOGY OF THE LAKE MICHIGAN BLUFFS
FROM WILMETTE TO WAUKEGAN, ILLINOIS
Illinois State Geological Survey
The 30- to 100-foot high bluffs that extend along the lake shore
from Wilmette to Waukegan provide excellent vantage points of the lake,
adding appreciably to the value of lakefront property. With lakefront
exposure, however, come the hazards of bluff erosion which are especially
evident during periods of high lake levels. The rapid recession of portions
of the bluff has led the Illinois State Geological Survey, as part of a broad
coastal data gathering program, to begin a series of studies to determine the
rates, locations, and reasons for abnormal bluff erosion by means of synoptic
aerial surveys, stratigraphic analyses, and measurements of engineering proper-
ties such as slope, water content, compressible strength, Atterberg limits,
and mineral composition.
Six borings spaced every few miles along the bluff have been com-
pleted thus far (fig. 11) and more are scheduled. The holes were drilled
within a few hundred feet of the bluff for the purpose of correlating sub-
surface data with descriptions and analyses made of samples taken from the
Dames and Moore, Consulting Engineers of Park Ridge, Illinois, are
cooperating in the study through the participation of Allen Perry, who will use
portions of the study for a Ph.D. research program. Engineering tests of
samples are being carried out by the Illinois State Geological Survey and
Dames and Moore.
Extensive soil property data are essential to good design practice
in construction but funds for acquisition are limited. Consequently, plans
call for taking full advantage of information already in the files of local
engineers and consultants. Preliminary discussions with some of these firms
indicate a ready willingness that this data be used to advantage in the study.
The goals of the engineering geology study are to correlate the
stratigraphy and engineering properties of the bluffs and to make the results
available through a cumulative central file as well as through publications
and conferences. A better understanding of the materials in the bluffs will
greatly enhance the success of structural and nonstructural plans instituted
along the Lake Michigan shore and in time may lead to a stabilized and well
managed coastal zone.
■. ' ' ^ ' *
— — — -
/- s /-
v- x /
- N /- s
- x /-
1* ~1 >
" / '.i /
LOCATION OF CORES
• / V i
y 1 ^7'
, Vn / v
___ _ '
y »N -
% lllite and core
Fig. 11 - Diagram of materials encountered in research borings in the
Northshore bluff. Locations are shown in the inset index map.
EROSION OF TILL BLUFFS: WILMETTE TO WAUKEGAN
Jerry A. Lineback
Illinois State Geological Survey
The physical interaction between Lake Michigan and its shoreline
commonly works to the detriment of the shore, especially during periods of high
water level. Consequently, erosion is presently taking place at many sites
along the shoreline in Illinois. Many factors affect the extent and location
of the damage. Among these are waves and currents, water levels, orientation
and topography of the shore and nearshore, composition of materials comprising
the shore, and the extent and configuration of man-made structures.
The portion of the Lake Michigan shore from Wilmette to Waukegan is
lined with bluffs composed of till (Wedron Formation) with intercalated sands,
silts, and clays. The till bluffs rise from about 10 meters (30 ft) above the
lake just north of Wilmette to about 30 meters (100 ft) near Highland Park. The
topography results from the presence of the Highland Park Moraine, one of the
Lake Border Moraines, that was deposited as the Woodfordian age glacier began to
withdraw from Illinois about 13,500 radiocarbon years B.P. (fig. 12). The
material in the moraine is mostly till with several intercalated beds of glacial-
lacustrine silts and sand, and some sandy glacial outwash. All are assigned to
the Wadsworth Till Member of the Wedron Formation. At least three till beds can
be identified (fig. 13), and all have similar characteristics and composition.
North of Highland Park, the till is overlain by lacustrine sand and silt
(Equality Formation) deposited when one of the early stages (Glenwood) of an-
cestral Lake Michigan stood at about 195 meters (640 ft) above sea level. The
till contains very little gravel and larger sized material (table 2) . The matrix
contains 5 to 20 percent sand. Silt and clay comprise the remainder, with clay
slightly more abundant than silt. Illite is the dominant clay mineral. The till
is layered in places with bedding thickness of 30 centimeters. It is gray or
brown, and, where the till is brown, it commonly contains more pebbles.
TABLE 2— AVERAGE COMPOSITION OF THE WADSWORTH TILL MEMBER
OF THE WEDRON FORMATION IN NORTHSHORE BLUFFS
Sand 10%, Silt 42%, Clay 48%
Clay minerals in <2u fraction
Expandables 7%, Illite 73%, Kaolinite-Chlorite 20%
Carbonate minerals in <2u fraction
Calcite, 42 counts per second; Dolomite, 57 counts per second
SE'/4, NW'/4, Sec. 3, T 43 N, R 12 E
Gravel , sandy
Till, si Ity c lay ,
Sand, f i ne to medium
grai ned, si I ty ,
Till, si Ity c lay,
gray, some pebbles
NE'/4, Sec. 16, T 44 N, R 12 E
Sand, gravel I y
si I ty sand
Silt, sandy silt,
s i I ty sand, mostly
s I umped
- V \ / I «/ \ Ti I I, si Ity, gray
Silt, clayey, till?
pebb I es
Fig. 12 - Representative stratigraphic sections from the northern part
of the till bluff area showing multiple till units in the
Wadsworth Till Member.
The primary use of the shore between Wilmette and Waukegan is low-
density residential, with two military installations (Fort Sheridan and the
Great Lakes Naval Training Center) . The bluff is oversteepened by wave erosion
at the base, and about 10 percent of the bluff line is presently undergoing
active erosion with slumping and recession of the top of the bluff (plate 4) .
Most of the rest of the bluff has suffered some damage but is partially pro-
tected by man-made structures and vegetation. The shore from Waukegan north
to the state line consists of a more or less stabilized till bluff or high-
level lake plain underlain by till, with an extensive beach ridge complex up
to 1.8 kilometers (1.1 mi) wide between the bluff and the lake.
Inclusions of pebbly silt in the till are present in places and are
more easily eroded by wave action than is the till. Beds of stratified material
between beds of till range from a few centimeters to several meters in thick-
ness. They range from massive silt to sand with large scale cross-bedding.
The amount of water-laid material is greatest between Lake Bluff and the
Great Lakes Naval Training Center. Beds of stratified material are less stable
in the slopes than in the till and contribute to slumping. Springs and seeps
along the bluffs indicate that ground water is moving through the sediments;
increased pore pressure from ground water contributes to the slumping of the
High lake levels tend to accelerate lake shore erosion around the
Great Lakes. Lake Michigan exhibits seasonal fluctuations of about 30 centi-
meters. The peak high occurs in late summer. Since 1860, recorded lake levels
show long-term fluctuations of about 2 meters with periods ranging from 8 to
20 years between highs. High levels are reached during and just after periods
characterized by high precipitation in the lake region. The present lake level
is about as high as any recent recorded levels. As a result, accelerated erosion
is taking place. The chief effect is the removal of the wide sand beach that
protects the shore at low water levels, undercutting of the till where waves
beat directly on the toe of the bluff, slumping by the upper bluff, and removal
of the slumped materials by longshore and offshore currents (pi. 5).
Erosion rates vary from place to place depending on local conditions.
Much of the till bluff presently shows little slumping and erosion. About 10
percent of the bluff line, however, has been denuded of its vegetation and is
rapidly being removed. Long-term (1939-1964) recession rates of the bluff,
measured from aerial photographs, range from zero to about 1.5 meters (5 ft)
per year. As much as 122 meters (400 ft) of recession per year has been recorded
during historic times.
Sediment generated by wave erosion is large in volume but is rapidly
removed from the area, permitting continued erosion. Sediment dispersal patterns
can be determined by observing bands of turbid water in the lake from earth-
orbiting satellites. Data for 18 days between August 1972 and August 1973 have
been recorded by the ERTS-1 satellite and related to local wind conditions. The
dominant wind direction (39 percent of the time) is from the southwest. Pre-
vailing southwesterly winds tend to move water and suspended sediment from the
nearshore zone toward the northeast (pi. 6 and facing fig. 13). Several images
show that these northeasterly trending sediment plumes turn to the southeast
several miles offshore where they meet the southward moving longshore current.
The net loss of sediment is to the south, and the sand appears to be distributed
over the nearshore lake floor. Only very coarse material is retained along the
shore during high lake levels. During low lake levels, however, sand accumulates
in the beach zone and finer materials are removed offshore.
About 10 percent of the till bluffs between Wilmette and Waukegan are
undergoing active erosion. The remainder have been damaged but are protected
by sea walls or vegetation. Present high lake levels have resulted in waves
and currents removing the protective sand beach, allowing direct access for
waves to the toe of the bluff. Sediment derived from erosion is carried from
the shore by combination of wind-induced currents and longshore drift. Accel-
erated erosion will continue until the water level drops to the point where a
significant beach can be reestablished. Rates of bluff recession range as high
as 1.5 meters (5 ft) per year in areas of active erosion.
Significant erosion is taking place along unprotected segments of
the Lake Michigan shoreline. The pictures show the changes that
occurred between August 1973 (top picture) and March 1974 (bottom
picture) at a location on the shore between Elder Lane Park and
Lake Front Park in Winnetka, Illinois (center south line NE^ Sec.
21, T. 42 N. , R. 13 E.). The August picture shows a new vertical
wave-cut face at the toe of the bluff. The beach is narrow, and
no structures prevent waves from striking the bluff. Lenses of
gravelly silt in the till are easily eroded and create pockets along
the bluff. Note the position of the large forked tree. The bottom
picture was taken after winter storms and shows that the over-
steepened bluff has slumped. The toe is covered with slump debris
and the top part is nearly vertical. The forked tree and a sig-
nificant portion of yard have been removed.
Aerial photographs taken in 1964 (A) and 1973 (B) of a portion of
the till bluffs near Fort Sheridan, showing that the wide beach
present in 1964 has largely been removed during the high-water
levels of 1973. At Station 1, 11.6 meters (38 ft) of beach was
lost; at Station 2, 28.3 meters (93 ft); and at Station 3, 15.2
meters (50 ft). At Station 4, 23.8 meters (78 ft) of beach and
10.4 meters (34 ft) of bluff have been removed.
Fig. 13 - Interpretive diagram of enhanced ERTS-1 frame 1124-16050.
caption to plate 6 for explanation.
Enhanced ERTS-1 frame 1124-16050 (opposite page) and interpretive
diagram (above) , multispectral scanner band 5 (red) , taken
November 24, 1972, showing sediment plumes in Lake Michigan
between Wilmette and Waukegan. Arrows indicate direction of
sediment plume growth. Numbers indicate relative density of
suspended sediment. The number 5 indicates maximum density;
1 indicates minimum.
LATE HOLOCENE LAKE LEVELS IN SOUTHERN LAKE MICHIGAN
Curtis E. Larsen
University of North Carolina, Wilmington
The return of high lake levels in recent years has greatly revived
interest in the prediction of future high water levels and with it the topic
of Holocene lake levels by which future levels may be judged. The highly de-
tailed studies of raised beach features originally reported by Leverett and
Taylor (1915) form the base of the classic literature. In the 1950s, Bretz
(1955) and Hough (1958) reopened this research wherein complex models of
crustal deformation and movements of major ice fronts were invoked to explain
a vast number of relict coastal and fluvial features. It is now apparent that
much of this early work, while provocative and informative, lacked the precise
temporal control now available through improved C dating techniques. In
addition, more is known today regarding ongoing post-glacial isostatic rebound
in the Great Lakes region (Clark and Persoage, 1970).
Lewis (1969, 1970) recently provided a collection of C dates from
late Holocene beach features and stratigraphic sections for northern and
southern Lake Huron. These provide important evidence for the time of occur-
rence of the traditional Lake Nipissing (elev. 183 m/600 ft) and Lake Algoma
(elev. 180 m/591 ft) stages of Lake Michigan-Huron. In brief, Lewis placed
the Lake Nipissing stage between 5500 and 3900 ^C years ago. By the latter
date, the lake had dropped to the Lake Algoma level that was maintained until
about 2500 lh C years ago. The present level of 176.8 meters (580 ft) was
attained sometime after this period. This model is based largely on those of
Leverett and Taylor (1915) and Hough (1958).
The purpose of this research has been to pursue similar chronological
studies on the southern shores of Lake Michigan. In addition to the lack of
llf C control there, the area is well south of the Lake Nipissing and Algoma
"hinge lines" of Leverett and Taylor (1915) and Hough (1958) and hence poten-
tially undisturbed by active glacial rebound (see, for example, the model of
Clark and Persoage, 1970). Thus, the southern Lake Michigan record of late
Holocene lake level events may be preserved in greater detail than elsewhere
because it has been little influenced by crustal movements.
Three previous studies have suggested the occurrence of a variety of
post-Algoma lake level fluctuations. Detailed stratigraphic studies made in
connection with archeological excavations near the Straits of Mackinac
(McPherron, 1967) and in Saginaw Bay, Michigan (Speth, 1973) indicate the
presence of two separate high lake levels as much as 2 meters (6.6 ft) above
the present level (176.8 m/580 ft). More recently, Illinois State Geological
Survey studies have documented a similar high fluctuation that may have taken
place about 1200-1400 A.D. (Hester and Fraser, 1973; Fraser and Hester, 1974).
The latter evidence came from a beach-ridge complex located between Kenosha,
Wisconsin, and Waukegan, Illinois. These authors also reported important evidence
of peat from the base of an inter-ridge marsh at an elevation of 175.6 meters
(574 feet) — a suggestion of an extended low fluctuation of at least 2 meters
(6.6 ft) below the present level which occurred about 785 A.D. Traditional
models account for the drop in lake level from Lake Nipissing (183 m/600 ft)
to Lake Michigan -Huron (176.8 m/580 ft) by means of differential erosion of
outlets at Port Huron and Chicago. No provision, however, was made for extended
lake levels below elev. 176.8 meters (580 ft).
While no definitive evidence is presented here, pending results from
20 new C samples now being processed, it is nevertheless possible to draw a
broad outline of late Holocene lake levels based upon 16 recent and 3 earlier
but pertinent dates. These are tabulated in table 3.
Field work was carried out between Kenosha and Waukegan during the
spring of 1974 with special emphasis directed toward investigating specific
landforms — the beach-ridge complex and tributary streams west of the complex.
Gores were taken in inter-ridge marshes north of Illinois Beach State Park
(fig. 14). In each core, marsh peats or organic sands were found overlying
beach or nearshore sands. Radiocarbon dates on these organic deposits give
an approximate date of their formation as well as a younger limit for the age
of the underlying sands . Prior lake levels that formed the underlying beach
and nearshore deposits probably were no higher than the elevation encountered.
A combination of these data provides a tentative basis for reconstructing
recent past fluctuations. Of great value in the reconstruction is evidence
for a distinct north-south progression of successive beach ridges. This relation-
ship was suggested by Hester and Fraser (1973) and is verified here. The pre-
liminary time-space deposition scheme is presented in figure 14. Dated ridge
sequences south of cores 8 and 9 are based on unpublished archeological infor-
mation. The 1872 shoreline is derived from U.S. Army Corps of Engineers data
Stratigraphic sections were described along four tributary streams.
In the case of Barnes Creek south of Kenosha, a 3 meter (9.8 ft) section is
generally exposed across the sand body in an east-west stream cut. Part of
this section (columns 1 to 4) and several cores (columns 5 to 9) taken from
marshes are shown in figure 15. With the exception of Barnes Creek, C dates
are not yet available for alluvial fill samples that may date terraces. There
appear to be, however, at least three post-Nipissing terrace systems. These
are found at 2.4 meters (8 ft), 1.4 meters (4.5 ft) and 0.75 meters (2.5 ft)
above the existing stream beds and were found in at least three of four stream
systems observed. In addition, organic silts containing abundant wood fragments
and branches have been observed to extend upstream to about elevation 183 meters
(600 ft) in three of the stream systems. These silts are interpreted as marsh
deposits caused by ponding of water downstream because of temporary obstruction,
or more likely, a higher lake level. The elevation of these deposits suggests
that they are referrable to the Lake Nipissing stage. Alluvial terraces prob-
ably also result from base level changes caused by lake level fluctuations.
TABLE 3— RADIOCARBON DATES
Lab no. Material Age in C years
at time of
Illinois Beach State Park*
Beach Ridge Complex ^
ISGS-259 Wood 4740 ± 75 B.P.
ISGS-260 Wood 4890 ± 75 B.P.
ISGS-263 Organic 560 ± 75 B.P.
North Branch Channel, Chicago River //
Hester & Fraser, 1973
Hester & Fraser, 1973
Hester & Fraser, 1973
Hester & Fraser
Hester & Fraser
Hester & Fraser
Barnes Creek, Wisconsin^
4300 ± 75 B.P.
North Branch Channel, Chicago River
W-425 Wood 5370 ± 200 B.P.
Michigan City, Indiana H
1-362 Wood 5475 ± 250 B.P.
1-363 Wood 6350 ± 200 B.P.
Willman & Frye, 1970
TABLE 3— RADIOCARBON DATES— Continued
*Peats are from the base of extensive inter-ridge marshes west of park. Below
the peats are beach and nearshore sands with an undulating surface similar to
the present ridge complex.
tISGS-189 was obtained on wood from a paleosol exposed along the shore just
south of South Park. Wood has been identified as oak and ash and has been
published elsewhere with a 6340 ± 300 B.P. date (Sander, 1969). ISGS-185
and 187 were made on redeposited material from nearshore sand overlying
ISGS-189. The sequence shows a post 6340-5315 B.P. transgression of the lake
to 177 m (580 ft), but more exact dating of the in-place material is necessary.
^Peats and organic sand are from inter-ridge marshes north of Illinois Beach
State Park. Marshes here are also underlain by beach and nearshore sands.
^Both wood samples are from marsh silts overlying stiff lake deposits and glacial
till. These silts are overlain by fluvial sands and gravels, and beach or near-
shore sands. A paleosol developed on the nearshore or beach sands furnished
//Shell is from "Unio bed" discovered by F. C. Baker in 1914 (Baker, 1920).
Depth range for Elliptio crassidens in this assemblage is 1.5 to 6m (4.9 to
19.7 ft). This implies a possible lake level of 183 m (600 ft). W-425
was done on wood from marsh deposits underlying the "Unio bed."
UDate 1-362 is from upper of two marsh clay-silts that outcrop along beach west
of Michigan City. Ostracod genus Cyclocypris and grass fragments suggest marsh
environment. Lake surface was near or below elev. 177.2 m (581 ft) at time
of deposition. This bed is overlain by 3 to 6m (9.8 to 19.7 ft) of nearshore
sand. Date 1-363 is from lower of two clay-silt beds discussed above. Lake
surface is inferred to be at or below elev. 176.0 m (577 ft) at the time of
deposition. Lacustrine sand separates both clay-silt beds, perhaps indicating
a brief transgressional event or an isolated storm.
Fig. 14 - Diagram showing preliminary age determinations for beach
ridges in the Zion Beach Ridge Complex based on radiometric
and archaeologic dating. Approximate shorelines are also
given for the Glenwood, Nipissing, and Algoma Lake Stages.
Numbered dots refer to sections given in figure 15.
More information on lake level changes in southern Lake Michigan
comes from Chicago and Michigan City, Indiana. Sections exposed during the
excavation of a canal between Lake Michigan at Wilmette and the Chicago River
were discovered by F. C. Baker in 1914 (Baker, 1920). Certain of these ex-
posures were reexamined by the author and were sampled. In addition, mollusk
shells collected by Baker and deposited with the Illinois State Geological
Survey were dated. Most significant was a 4300 ± B.P. date (ISGS-266) from
the "Unio bed" continuously exposed for up to 3 kilometers (1.86 mi) near
Foster Avenue. Pelecypods and gastropods create a thick zone on top of a
sand and gravel layer that varies in elevation from 177 meters (580 ft) to
179 meters (587 ft) . The presence of Elliptio crassidens in this assemblage
calls for a depth of 1.5 meters (4.9 ft) to 6 meters (19.7 ft) in clear moving
water (Baker, 1920). This implies a lake level as high as 183 meters (600 ft)
for this period. Marsh silts containing branches and twigs below the "unio
bed" were dated by Leighton at 5370 ± 200 B.P. (Willman and Frye , 1970).
These dates mark a rise to the Lake Nipissing high from a level near the present.
Dated sections at and below present lake level near Michigan City,
Indiana, show marsh deposits containing grasses, wood, and shallow water ostracod
faunas. Two distinct beds are separated by lacustrine sands. The lower silt
dates at 6350 ± 200 B.P. (1-363) while the upper is 5475 ± 250 B.P. (1-362 in
Winkler, 1962). This section is in turn overlain by 3 meters (9.6 ft) to 7 meters
(22.4 ft) of beach and nearshore sand. A lake level slightly below the present
may be indicated by marsh silts. The overlying nearshore sands indicate a
later lake level of 183 meters (600 ft) . This is consistent with dated
stratigraphy at Chicago.
Figure 16 is a preliminary interpretation of late Holocene lake levels
for Lake Michigan-Huron based upon the information collected thus far. While
the overall downward trend is similar to earlier conceptions, the presence of
major fluctuations is not. It seems plausible that earlier researchers may
have derived their late Holocene interpretations essentially from evidence of
past high lake levels.
Paleoclimatic changes may offer an alternative to traditional models
that rely on crustal deformation to explain the Lake Nipissing high lake level
of Lake Michigan-Huron. A downward trend to the near present level can also
be explained using the same methods. The Nipissing high as well as post-Algoma
highs reported by Speth (1973) , McPherron (1967) , and Hester and Fraser (1973)
appear to be synchronous with well established periods of glacier expansion
in the northern hemisphere (Denton and Karlen, 1973) . The more recent of these
is the historically documented "Little Ice Age" of northern Europe. Hester and
Fraser' s (1973) peat date of about 785 A.D. from 175 meters (574 ft) also
appears to coincide with a period of warming documented by Denton and Karlen
Theoretically, this would identify high lake fluctuations with periods
of cooler temperature, and low fluctuations with corresponding warm periods.
In essence, Lake Michigan-Huron levels may provide an indication of late
Holocene climates, and therefore should be studied in far greater detail than
in the past.
Z M i-l
Straits of Mackinac
Saginaw Bay, Michigan
\ 7 y \?
H3_| Dated horizons
6 5 4 3 2
Thousands of calendar years before present
(corrected per Damon et a I., 1972)
Fig. 16 - Fluctuations in late Holocene lake levels in southern Lake
Perhaps more important to the potential solution of current environ-
mental problems, fluctuations in lake level appear to indicate long-term trends
that are not discernible in the historic record. Statistical data for deriving
lakeshore design criteria are generally based on the record of 114 years of
lake level changes. Holocene climatic influences on lake level are widely
assumed to have been similar to those recorded during the past century and to
have been superimposed on a downward trend of lake levels due to erosion of
outlet channels (see, for example, Hough, 1958). The data shown here in a very
preliminary way, however, indicate that serious flaws are inherent in any
interpretations that do not take climatic factors into account in reconstructions
of lake history or do not take prehistoric Holocene lake levels into account
in predictions of future lake levels.
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Illinois State Geological Survey Bulletin 94, 204 p.
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