Illinois Natural History Survey - University of Illinois

CRETACEOUS HILLS 

Cardinal flowers in the Cretaceous Hills RRA, photo by Mike Jeffords, INHS Cretaceous Hills is an area of low, gravel hills. Acidic seeps, which support some of the most interesting natural communities in the state, are found in this area. Seeps are caused when groundwater, percolating through this gravel, flows to the surface where it meets underlying sandstone. An abundant and diverse flora grows in these moist areas, including many unusual and rare species of orchids, mosses, and ferns, some with four foot-long fronds.

Map of Site
Land Cover Map of Site

SIZE: 89,928 acres; 137 square miles

LOCATION:Southeastern tip of Illinois along the Ohio RIver; Massac and Pope counties.

The Cretaceous Hills RRA encompasses the southeastern tip of the state. The area is characterized by rolling hills of sand, gravel, and clay and bottomlands along the Ohio River.

In the Ohio River floodplain are areas of cypress swamp, floodplain forest, and flatwoods. Flatwoods are forests growing on hardpan clay, a soil that is wet in spring and dry and hard in summer. The trees are relatively small, reflecting the harsh soil conditions, and they tend to blow over because of their shallow root systems. The nature preserve in Fort Massac State Park has a large flatwood forest comprised of pin oak, swamp white oak, and post oak.

LANDCOVER : Predominant landcover types are cropland (32%), upland woods (31%), and grassland (24%). This site ranks fourth in percentage of upland woods, ninth for grassland, and fifth for bottomland woods. It has one of the lowest acreages for nonforested wetlands.

NATURAL AREAS : There are 19 Natural Areas. Important natural features include barrens, springs, lakes, ponds, and flatwoods.

BIOLOGICALLY SIGNIFICANT STREAMS : Two stretches of the Ohio River totalling 14 miles are designated as BSS streams.

HERITAGE SITES : There are 74 Heritage occurrences. Seven community types, 25 plant species, ten animal species, and two rookeries are located in this RRA.

STATE AND FEDERAL LAND : Fort Massac State Park is the only state land in this RRA. Federally owned land consists of 12,000 acres in the Shawnee National Forest.

NATURE PRESERVES : Significant features in the two Nature Preserves are slope, ridge, and ravine forests, seep springs, cypress swamp, floodplain forest, and flatwoods.

NATURAL DIVISIONS : This RRA is 89% in the Coastal Plain Division and 10% in the Shawnee Hills Division.

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

Total Acreage

    87,928

Natural Areas

    Acreage

    1,940

    Number

    19

Biologically Significant Stream Mileage

    14.1

Natural Heritage Sites

    74

State Land

    State Parks

    1

    State Conservation Areas

    0

    State Forests

    0

    State Fish & Wildlife Areas

    0

    Acreage

    619

    Percentage of RRA

    0.7

Federal Land

    Acreage

    11,999

    Percentage of RRA

    13.6

 


 

LANDCOVER

    Acres

    % of RRA

Upland forest

    27,471.32

    31.24

Bottomland forest

    8,315.74

    9.46

Wetland-nonforested

    412.86

    0.47

Grassland

    20,896.33

    23.77

Cropland

    28,118.41

    31.98

Urban/Built-up

    357.46

    0.41

Water

    2,353.70

    2.68

TOTAL

    87,925.82

    100.01

 


 

ILLINOIS NATURAL AREAS INVENTORY SITES Acres
Burke Branch Research Natural Area 167
Caney Creek Site *
Cave Creek Barrens *
Clear Lake 40
Cretaceous Hills 449
Dean Cemetery East Barrens *
Dog Creek Barrens *
Fort Massac Area 183
Kickasola Cemetery Barrens and Springs *
Klondike Spring 3
Lewis Estate 355
Lewis Estate North 404
Lewis Estate South 44
Massac Tower Springs 45
McGhee Flatwoods *
Poco Cemetery Barrens East 1
Poco Cemetery Barrens North *
Round Pond 247
Snow Springs 1
* = point location, map not available

 


 

BIOLOGICALLY SIGNIFICANT STREAMS

    Miles

Ohio River, L&D 52 to Metropolis

    2.8

Ohio River, at mouth of Cumberland River

    11.3

 


 

NATURAL HERITAGE CATEGORIES
Communities Occurrences Types/Species

    Floodplain Forest

3 2

    Lake

1 1

    Wetland

5 2

    Savanna

8 2
Threatened and Endangered Animals

    Bird

3 2

    Fish

3 2

    Mammal

2 1

    Reptile

1 1

    Mollusk

4 4
Threatened and Endangered Plants

    Plant-Dicot

23 13

    Plant-Monocot

18 11

    Plant-Fern/Fern Ally

1 1
Geological Feature
Other

    Rookery

2 1

 


 

STATE AND FEDERAL LAND
State Parks

    Acres

    Fort Massac

    619

State Conservation Areas

    0

State Forests

    0

State Fish and Wildlife Areas

    0

Federal Land

    Shawnee National Forest Proclamation Boundary

    30,851

    Shawnee National Forest Ownership

    11,999

 


 

ILLINOIS NATURE PRESERVES

    Acres

Cretaceous Hills

    272

Massac Forest

    156

 


 

NATURAL DIVISIONS

    Acres in RRA

    % of RRA

    % of Division

Coastal Plain

    78,285

    89.3

    16.9

Shawnee Hills

    8,824

    10.1

    0.9




Illinois Natural History Survey

1816 South Oak Street, MC 652
Champaign, IL 61820
217-333-6880
cms@inhs.illinois.edu

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