Illinois Natural History Survey - University of Illinois

BIG RIVERS 

Bald Eagle in the Big Rivers RRA, photo by Mike Jeffords, INHS The three areas in Illinois that were not covered by glaciers are the northwest corner, the far south, and the area where the Illinois River joins the Mississippi River. Glaciers did, however, influence these nonglaciated areas. In addition to rock and sand, meltwater deposited a finely ground silt which dried to a dust called loess. Windblown loess deposits along the lower Illinois River are among the thickest in the state. Several loess hill prairies occur in Big Rivers. A layer of loess, sometimes 150-feet thick, forms steep slopes and vertical cliffs.

 

Map of Site
Land Cover Map of Site

SIZE: 626,795 acres; 979 square miles

LOCATION:Western Illinois, upriver of the confluence of the Illinois and Mississippi rivers; Adams, Calhoun, Greene, Jersey, Madison, Pike, and Scott counties.

Big Rivers is the largest of the RRAs. The area is characterized by a narrow band of bluffs and rugged topography that borders the floodplains of the Mississippi and Illinois Rivers. Forest is the predominant natural vegetation; hill prairies are common on western facing bluffs. Sinkholes and sinkhole ponds occur here.

LANDCOVER : Cropland is the predominant landcover type (42%) of the site, followed by upland woods (24%). Big Rivers has the highest bottomland woods acreage and the third highest upland woods acreage among the RRAs; it ranks seventh in percentages of both bottomland and upland woods. It has moderate nonforested wetlands resources.

NATURAL AREAS : Sixty-one Natural Areas, totaling 10,514 acres, are located in this RRA. The largest is Gardner Woods with 4,468 acres. Significant features include hill prairies, aquatic systems, woods, geological areas, glades, and caves.

BIOLOGICALLY SIGNIFICANT STREAMS : Twenty miles of Hadley Creek and nine miles of the Mississippi River are designated BSS.

HERITAGE SITES: There are 150 Heritage sites within this RRA representing seven significant community types, 11 plant species, 23 animal species, and eight rookeries.

STATE AND FEDERAL LAND: The state and federal governments own 47,448 acres. Most is federal land divided among Mark Twain National Wildlife Refuge and the pools of the rivers. Pere Marquette State Park and Calhoun County Conservation Area are state land located in this RRA.

NATURE PRESERVES : There are five Nature Preserves in this RRA. Communities protected in the preserves are bluffs, sink holes, ravines, bedrock outcrops, upland forest, and hill prairie.

NATURAL DIVISIONS : This site contains five natural divisions, predominantly the Middle Mississippi Border and Upper Mississippi and Illinois River Bottomlands.

SUMMARY OF SITE CHARACTERISTICS: SIZE, BIOLOGIC RESOURCES, AND PUBLIC LAND

Total Acreage

    626,795

Natural Areas
Acreage 10,514
Number 61
Biologically Significant Stream Mileage 28.9
Natural Heritage Sites 150
State Land

    State Parks

1

    State Conservation Areas

1

    State Forests

0

    State Fish & Wildlife Areas

0

    Acreage

9,547

    Percentage of RRA

1.5
Federal Land

    Acreage

37,901

    Percentage of RRA

6.0

 


 

LANDCOVER

    Acres

    % of RRA

Upland forest 147,380.80 23.51
Bottomland forest 48,335.94 7.71
Wetland- nonforested 3,943.51 0.63
Grassland 90,915.57 14.51
Cropland 263,995.60 42.12
Urban/Built-up 23,125.79 3.69
Water 49,085.98 7.83
TOTAL 626,783.19 100.00

 


 

ILLINOIS NATURAL AREAS INVENTORY SITES

    Acres

Alton Geological Area 7
Atlas South Geological Area 7
Beebe Creek Site *
Belleview Site 8
Brainerd Cave 3
Brewster Hill Prairie 3
Browning Hill Prairie 45
Cap Au Gris 98
Chautauqua Prairie 126
Cincinnati Landing Site 164
Clarksville Island 820
Deer Lick Hollow Geological Area 7
Del Air Area *
Distillery Hollow Glade 40
Drift Island 541
Eldred Caves 12
Emma Brown Hill Prairie 3
Gardner Woods 4,468
Gilbert Lake 11
Golden Eagle Geological Area 2
Grubb Hollow Prairie 14
Hadley Creek 202
Hamburg Southeast Geological Area 1
Horton Creek Hill Prairie 4
Jennings Hill Prairie 2
Jimtown Branch Geological Area 5
John Craig Hill Prairie 8
Kamp's Glade 214
Kinderhook Hill Prairie 5
Krause Woods 81
Lead Hollow Glade 22
McAdams Peak Hill Prairie 252
McNabb Hollow 28
Mississippi River -Cap Au Gris 1,431
Mississippi River -Pike *
Monterey School Geological Area 17
Mortland Glade 101
Motley Hill Prairie 6
Mozier Slough 34
North New Canton Hill Prairie 20
Olin Tract 244
Osterman Hill Prairie 13
Pearl Limestone Quarry 11
Pearl Prairie Geological Area 4
Pere Marquette Bald Eagle Habitat 492
Pilot Knob Limestone Glade 4
Pleasant Hill Hill Prairie 1
Principia Hill Prairies East 480
Principia Hill Prairies West 101
Quincy Geological Area 4
Riprap Landing Woods 179
Royal Landing 30
Shaffer Hollow Hill Prairie 36
Shewhart Hollow Hill Prairie 23
Swarnes Hill Prairie 39
Teneriffe School Geological Area 4
Twin Culvert Cave 4
Two Branch Hollow Hill Prairie 10
Walnut Grove Hill Prairies 3
West Point Landing Geological Area 15
Wildcat Hollow North Geological Area 5
* = point location, map not available

 


 

BIOLOGICALLY SIGNIFICANT STREAMS

    Miles

Hadley Creek, upstream of McCraney Creek 19.9
Mississippi River, below L&D 25 9.0

 


 

NATURAL HERITAGE CATEGORIES
Communities

    Occurrences

    Types/Species

    Floodplain Forest

6 2

    Cave

4 2

    Forest

1 1

    Prairie

24 1

    Primary

5 1
Threatened and Endangered Animals

    Amphibian

1 1

    Bird

24 8

    Fish

4 2

    Mammal

15 4

    Reptile

6 2

    Insect

2 2

    Mollusk

9 4
Threatened and Endangered Plants

    Plant-Dicot

19 8

    Plant-Monocot

8 3
Geological Feature

    Geological Feature

14 1
Other

    Rookery

8 1

 


 

STATE AND FEDERAL LAND
State Parks

    Acres

    Pere Marquette

8,168

    State Conservation Areas

    Calhoun County (Rip Rap Landing)

1,379
State Forests 0
State Fish and Wildlife Areas 0
Federal Land

    Mark Twain NWR -Gilbert Lake Division

789

    Mark Twain NWR

1,876

    Mark Twain NWR -Gardner Division

5,013

    Mark Twain NWR -Calhoun Division

2,130

    Pool No. 21

3,019

    Pool No. 22

4,418

    Pool No. 24

3,372

    Pool No. 25 (Inc. Reds Landing and Batchtown FWMA

5,208

    Pool No. 26 -Calhoun Point

2,317

    Pool No. 26 -Fuller Lake

1,702

    Pool No. 26 -Glades Hembold

954

    Pool No. 26 -Godar Diamond

2,808

    Pool No. 26 -Stump Lake

4,295

 


 

ILLINOIS NATURE PRESERVES

    Acres

Grubb Hollow Prairie 45
John M. Olin 230
Mississippi Sanctuary 38
Oblate Father's Woods 19
Pere Marquette 179

 


 

NATURAL DIVISIONS Acres in RRA

    % of RRA

    % of Division

Middle Mississippi Border 325,172 52.3 21.0
Upper Mississippi R and Illinois R Bottomlands 209,421 33.7 17.8
Western Forest-Prairie 35,421 5.7 0.8
Major Water Bodies 34,200 5.5 3.0
Lower Mississippi R Bottomlands 11,348 1.8 3.1
Illinois R and Mississippi R Sand Areas 5,912 1.0 1.5



Illinois Natural History Survey

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