The Sinkhole Plain
An Inventory of the Region's Resources
Illinois Department of Natural Resources
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A human needs a hammer to break it, but limestone is chemically very fragile, and with time a dribble of water can dissolve it and carry it away. In southwest Illinois, water percolating through cracks and fissures has eaten away at the limestone bedrock that here lies very near the surface. The landscape is riddled with underground cracks, crevices, and caves.
Water does not course upon such land, it courses through it. A gathering creek or stream may eventually disappear into a "swallow hole," where the stream seems to be swallowed by the earth. From there the water may flow into a cave until it bubbles out of the cave downhill in the form of a spring. Those spring waters may gather and form a new—or at least reconstituted—stream. Some springs in Monroe and St. Clair counties have been discharging water for approximately the past 11,000 years, and new ones are being discovered all the time. Early in this century, 88 springs were documented in Illinois; at present scientists have information on 300.
Often, subsoils are washed into the voids in the rocks below. Occasionally, the roof of a cave collapses. In both cases the surface slumps as its underpinnings collapse. The result is a sinkhole. The larger ones are as much as 25 feet deep—enough to swallow a house. There are an estimated 10,000 sinkholes in southern St. Clair, Monroe, and northern Randolph counties. In places they number 230 per square mile, so many that the landscape from the air looks like an old bombed-out battlefield. Geologists know such landscapes as "karst," but to most of its residents the region is known less exotically as the Sinkhole Plain. This is not the only karst landscape in Illinois—9 percent of Illinois has similar features—but it is the most extensive and interesting.
The region today
The Sinkhole Plain and its environs cover about 1,228 square miles in southwest Illinois, including all of Monroe County, much of St. Clair, and portions of Randolph and Madison counties. The Sinkhole Plain is the most distinctive ecological feature of this part of Illinois but by no means its only significant one. Bordered by two major rivers—the lower Kaskaskia River to the east and the Mississippi to the west—the region has examples of virtually every habitat known in Illinois, from floodplains lined by bluffs of exposed bedrock to prairies and wooded ravines, sluggish rivers, and clear-running springs. The region has some of the steepest terrain in Illinois (Richland Creek near Belleville drops ten feet per mile as it tumbles into the Kaskaskia) and some of the flattest (the lowest 36 miles of the Kaskaskia drop less than three inches per mile). The region likewise is a microcosm of Illinois's human communities. While most of the region is farmed, its northern one-third takes in the St. Louis suburbs of Collinsville, Belleville, East St. Louis, and Granite City, part of heavily urbanized Metro East.
While Illinoisan in its variety, the region is atypical in other ways. About 60 percent of the land area in and around the Sinkhole Plain is used for agriculture, while in Illinois as a whole nearly 78 percent of the land is farmed. The region has proportionately more trees, more wetlands, and twice as much urban and built-up land.
An estimated 6.9 percent of the Sinkhole Plain region consists of wetlands. A few are scattered across the uplands or in smaller stream bottoms, but most are on the bottomlands of the Mississippi and Kaskaskia rivers. Several are abandoned bits of riverbed known as "oxbow lakes"—so-called because they are shaped like part of an ox's yoke. The largest of these is the 2,000-acre Horseshoe Lake, which lies in that part of the massive floodplain of the Mississippi known locally as the American Bottoms.
Inevitably in such an intensely used landscape, the surface waters in and near the Sinkhole Plain have been stressed by pollution, sedimentation, and other ills. None of the region's natural lakes remains in top ecological condition, although most sustain sizable populations of game fish and birds. Two watercourses in the region have been recognized by scientists as "Biologically Significant Streams" because of the diverse life they support. One is a tributary to Horse Creek in Monroe County. One of several small streams in the Illinois Caverns, it runs over a gravel and bedrock bed and the clear water is home to several rare species of troglobytes, or cave-dwelling creatures. The other BSS stream is the sand-bottomed six-mile stretch of the Mississippi River in Randolph County. These two segments total a modest 6.9 miles in length, a tiny part of the approximately 2,380 miles of streams in the region. However, another nearly 50 miles of stream segments—Fountain Creek in Monroe County and Nine Mile Creek in Randolph County—earn a "B" for biological significance.
In the 1970s, surveyors of the Illinois Natural Areas Inventory (INAI) found 32 top-quality remnants of 17 presettlement natural community types in the region. The list included seven kinds of forest, glades, seeps and springs, and three kinds of prairies. The INAI surveyors also found 12 outstanding geologic areas, from limestone cliffs to exposed sandstone bedrock, sinkhole ponds, and caves. Nearly half of Illinois's surviving loess hill prairie is here. The 532-acre Fults Hill Prairie Nature Preserve in the Mississippi bluffs of Monroe County contains the largest complex of undisturbed prairie of this type in Illinois. It was named a National Natural Landmark by the U.S. Department of Interior in 1986. About 44 percent of the presettlement-quality wet floodplain forest still standing in Illinois is found in the region, as is more than a third of all southern flat-woods (in the Marissa Woods Nature Preserve in St. Clair County) and about 43 percent of the high-quality limestone glades.
In general, proportionately more presettlement nature survives in and around the Sinkhole Plain than in Illinois as a whole, in spite of the region's long occupation by humans. This is nature's doing, not humans, as the local landforms offer nature refuge on rocky bluffs and in caves that are largely safe from the plow and the parking lot. More than four of every five of the 1,075 plant species known from the region are native. (Statewide, 71 percent of the plant species are native.) However, while proportionately nearly twice as much presettlement habitat survives here as in Illinois as a whole, the acreage is very small—1,215 acres, less than two-tenths of one percent of what once was here.
Varied habitat means varied animal life. Mammals known from the region number 43 species, including the Indiana bat and river otter, whose survival in Illinois is considered to be endangered or threatened. Twenty-six amphibian and 44 reptile species are known or are thought likely to occur in the region; rare species include the Illinois chorus frog, the coachwhip snake, the timber rattlesnake, and the eastern massasauga. The waters of the region harbor 95 species of fishes, 29 species of native freshwater mussels, and 17 species of large crustaceans. At least 287 of the 300 species of birds that regularly occur in Illinois may be found in the Sinkhole Plain and its environs. Illinois's largest colonies of snowy egrets and little blue herons are here, as are some of the biggest colonies of great egrets and black-crowned night-herons. Here too are a few previously extirpated species such as the double-crested cormorant (which nests on the edges of backwater lakes along the Mississippi), the wild turkey, and the bald eagle, which have re-established themselves in recent years.
The Landscape: Before and after settlement
Humans live with the land, not just on it, and their presence has always changed the natural systems of which they are a part. For example, Native Americans of some cultures protected hickory trees to insure a supply of that much-desired nut.
They did this by cutting trees of species other than hickory for firewood and building, thus altering the species composition of local forests. And by setting prairies afire (to aid hunting), they killed off competing tree saplings and retarded the natural succession from grasslands to forest.
The pace of human-induced ecological change accelerated once Euro-American settlement began here in earnest in the mid-1700s. What happened to the local wetlands is typical. In 1820 or so, 24 percent of Monroe County, or more than 56,000 acres, was estimated to consist of wetlands of all types; today there are about 17,000 acres. St. Clair County's nearly 78,000 acres of wetlands dwindled to 33,000 today. In all, more than 87,000 acres of wetlands have been drained, most of it floodplain forest in the American Bottoms that was cleared for farms.
Trees in presettlement Illinois tended to be creatures of the bluffs and bottoms, and places like the Sinkhole Plain that had a lot of each were heavily wooded. Monroe County once was 87 percent forest, counting woods growing in wetlands. Roughly 70 percent of the region's land overall is thought to have been in forest around 1820, compared to 40 percent in Illinois as a whole. About 20 percent of the Sinkhole Plain and environs is wooded today, and only about 0.16 percent of that is covered by forest of high ecological quality.
Clearing for bottomland farms took its toll, but in the rugged uplands logging also was a factor; white and black oaks, for example, were sought by "tie hackers" which felled them and split them into railroad ties. Of the bottomland forest, 30,000 acres remain—a relatively significant inheritance in terms of acreage, although only 321 acres of it matches the quality of its presettlement predecessors.
About 30 percent of the land in and around the presettlement Sinkhole Plain was prairie. The larger prairie openings were local landmarks, such as Looking Glass Prairie near Belleville. (The novelist Charles Dickens visited there in 1842; no ecologist, he pronounced the scene "oppressive in its barren monotony.") A fair acreage of grassland still graces the region (14.4 percent of the land area) but these modern grasslands consist mainly of railroad rights-of-way, pastures, grassy roadside strips, hayfields, and the like. Only 173 acres is high-quality prairie, most of it unplowable hill prairie. That's 0.02 percent of the area, or less than one one-thousandth of the acreage that prairies covered in presettlement days. Savanna—a not-quite-forest, not-quite-prairie ecosystem in which scattered large trees (usually oaks) dominate an open landscape of prairie grasses and forbs—almost certainly was widely present (especially in the form of "barrens" that grew on thin soils atop the local limestone) but its exact extent is unknown.
Habitats cannot change so markedly in extent and quality without impelling changes in the numbers and variety of living things that depend on them. The list of local birds used to include species, such as the swallow-tailed kite, that have become extirpated since 1820. Other bird species are still present but no longer breed here, among them the trumpeter swan, osprey, least tern, and yellow-headed blackbird. The region harbors 75 plant and animal species whose survival is threatened or endangered, including five species whose survival is at issue not only in Illinois but in the U.S. as a whole. (The latter includes such plant species as the decurrent false aster, populations of which are found in St. Clair and Madison counties.) Of the T&E species, 36 are birds and 24 are plants. Another 12 are denizens of streams and wetlands—three freshwater mussels, two crustaceans, two fish, one amphibian, and four reptiles. One of the fish, the western sand darter, is fairly common in clear sandy runs of the upper Mississippi, but outside of that setting it survives in only a few places, including the Mississippi River just south of Prairie Du Rocher.
Some species tolerate human-altered ecosystems better than others. The prairie kingsnake is one, as are bullfrogs, most small mammals, and the familiar backyard birds. However, many plants and animals are adapted to very specific habitats and cannot cope if those habitats are altered significantly. One of Illinois's rare aquatic worms (a sludge worm) dwells only in springs such as are found at two sites in Monroe County and one site in St. Clair County. The Illinois chorus frog, known from Edwardsville and from the American Bottoms in Monroe County, inhabits only fishless ponds with sandy substrates—havens once common on Illinois's sandy prairies. As the ponds have become rare, so has the Illinois chorus frog.
The regional economy
Illinois's best soils were formed from loess, windblown silts originally deposited along the big rivers by glacial meltwater. The blanket of loess that lies atop the larger Sinkhole Plain region is thicker (in places more than 20 feet) than it is in much of the rest of this part of Illinois. However, the region's rough terrain makes efficient cultivation of field crops difficult. While more land is used for farming than any other single purpose, less of it is farmed than in Illinois as a whole.
Agriculture is fading in relative economic importance in the region. The number of farms has declined, consistent with state trends, but the amount of land in farms has dropped more than in Illinois as a whole, with the greatest percentage decline occurring in Monroe County—perhaps not coincidentally the county that has been urbanizing the fastest. While farming in rural areas is still a big employer, it occupies only 2 percent of the region's workforce, half its 1970 share. Earnings from farming have declined too, and farm property accounts for only 4.7 percent of the tax base in the three counties that make up most of the Sinkhole Plain. The rural economy used to keep Illinois towns alive; now it often is the other way around—Monroe County residents now earn more money outside the county than inside it.
Farmable soils are only one of geology's gifts to the area. Limestone bedrock is another. Five quarries crush the stone and sell it to the construction trade or as raw material for agricultural lime. High-grade calcium-rich limestone used by the cement and chemical industries is taken from underground mines near Prairie du Rocher ("Prairie by the Rock").
Coal mining was a major industry in the vicinity of the Sinkhole Plain. Coal was first mined in 1837 from the bluffs above East St. Fouis, where erosion had exposed the seams, and the industry enjoyed a heyday in the 1920s. Former surface mines and underground works dot the region, especially on its eastern edge. The earlier mines were simply abandoned, but their more recent successors have been reclaimed according to increasingly strict standards that began to take force in the 1970s. Coal is still plentiful but its quality does not appeal to today's buyers, and there is no active coal mining in the region.
Water is not usually thought of as a mineral resource like coal or stone, but buried water is essential to the economy of the region. As glaciers melted away, sands and gravels were washed into ancient river valleys, piling up there in beds as thick as 90 feet. Subsequently buried, these deposits became reservoirs of underground water that could be tapped by wells. The yields along the Mississippi are large enough to supply larger Sinkhole Plain towns such as Collinsville and Edwardsville. Houses and small towns in the upland rural districts tap water caught and held in the fissures and cracks of bedrock.
Wholesale land clearing has stopped, if only because there is little usable land left uncleared. The dumping of untreated sewage and industrial garbage into rivers has ended too. However, heedless human use of the land still compromises its ability to sustain a diverse array of living things over the long term. The main agents of landscape change are habitat degradation (caused by grazing, erosion, and pollution), habitat fragmentation, the suppression of natural fires, and—perhaps most important—urbanization.
Grazing Livestock that feed in forests kill many native plants treasured for their flowers or form, including ferns and wildflowers like orchids, miliums, and bellflowers. As a result, very few woods of the Sinkhole Plain region harbor the rich forest understory that persists in the William and Emma Bohm Memorial Nature Preserve in Madison County. The demise of native plants creates openings for aggressive exotic species such as multiflora rose and bush honeysuckle, whose extent in any given woods in Illinois appears to be proportional to the grazing it has received.
Erosion Erosion is a natural phenomenon. The picturesque ravines and bluffs that have always enchanted travelers are in fact the scars left after water had eaten away at exposed glacial debris and soft sandstone. However, humans have accelerated the process of topsoil movement. Beginning in the 1920s, most Sinkhole Plain farmers, like their colleagues across Illinois, quit raising small grains like oats and wheat in favor of crops like corn and soybeans that are grown in open rows, leaving soil exposed to the eroding force of water. Humans have also altered streams in a way that causes the water to claw more energetically at streambanks.
Much of the soil displaced by erosion ends up in streams, lakes, and ponds, often in such quantities that soil becomes, in effect, a water pollutant. The packed sand and gravel bottom of the lower Kaskaskia, where that river nears the Mississippi, is buried each summer beneath fine silt as much as a foot deep.
Erosion from fields has been much reduced since the 1980s. Row-crop acreage has declined, with several thousand acres of the region's hilliest, most erodible land taken out of production and turned into government-paid "conservation reserves." Also, the region's farmers have adopted soil-saving conservation tillage techniques, if somewhat less enthusiastically than have farmers in Illinois as a whole. By 1997 nearly six of ten acres of the area's farmland were losing soil no faster than it was being replaced by nature. This is a relatively sizable proportion, given how vulnerable the sloping farmland is to erosion.
Pollution Trends in area air quality over the past 25 years mirror those of the state as a whole. Federal regulations set maximum safe concentrations of certain air pollutants, such as lead and sulfur dioxide, that can threaten human health. The only violations recorded have been for ozone, in the middle 1990s, at two monitoring sites in urban areas.
Much progress has been made in reducing pollutants that enter area rivers and streams from "point sources" like factories and city sewer systems. Nonetheless, in general water quality in the region's streams and rivers remains only fair. Most of the pollutants are excess nutrients from partially treated sewage and fertilizer runoff from farm fields, both of which encourage the growth of bacteria that deplete life-giving oxygen dissolved in the water. The goldfish, an introduced species, is especially abundant in Harding Ditch in St. Clair County for the same reason that it is a good pet—it can thrive in water that would kill most other fish.
Groundwater is generally safe, although water taken from bedrock is too highly mineralized to be very desirable for drinking. Tests show that concentrations of six chemicals, such as iron or nitrates, that can render water unpalatable or unhealthy are within safe levels set by federal drinking water standards. However, the peculiar geology of the Sinkhole Plain poses unique risks of groundwater contamination.
Scientists sometimes liken karst landscapes to a Swiss cheese, sometimes to a honeycomb, sometimes to a sieve. The different metaphors describe a common reality. In most parts of Illinois surface soil acts as a massive filter, protecting subsoil and groundwater. In a karst area, water does not run atop the land, it runs through it. Water moves freely into and through the shallow limestone nearly as freely as water moves through a tile drain, taking mere hours to cover distances that take days or weeks in less porous formations. Water entering these rocks is not filtered or chemically buffered by slow seepage through upper layers of clays and sands, as is the case in many parts of Illinois. For example, part of the flow of Fountain Creek in Monroe County "sinks," meaning it directly enters the bedrock below through cracks in its bed.
As a result, there is a significant threat of contamination by pollutants spilled, dumped, or stored on the surface, from septic field discharges, road runoff, and pesticide and fertilizer runoff from farm fields. (Groundwater contamination has already caused much damage in eastern states such as Florida, where development has overrun once-virgin karst.) The growing number of houses built in rural areas means a growing risk of contaminating shallow-lying groundwater with coliform bacteria from ill-maintained septic systems. Nearly two-thirds of the systems in the region do not meet state codes for discharge. The lateral fields of many such systems discharge directly into sinkholes through which surface water enters shallow aquifers. A recent four-year Illinois State Geological Survey study sampled wells and springs throughout the Sinkhole Plain, and found that in the summer months 55 percent of 29 private wells drilled into bedrock contained higher-than-recommended levels of coliform bacteria, a common indicator of fecal wastes.
Since 1991 the Illinois Natural History Survey and the Illinois State Geological Survey have studied ten karst springs in Monroe and St. Clair counties. Scientists found nitrogen in all 40 water samples collected from the springs and at least one of four commonly used farm herbicides was detected in 33 of the 40 samples, although in none of the samples did the contaminants exceed the U.S. EPA's minimum safe levels.
It is not only humans that are potentially at risk from groundwater contamination. Each individual cave, sinkhole, or spring sustains its own ecosystem. Even after decades of collecting specimens, scientists do not have an exhaustive roster of animal life in the region. In the mid-1990s, a study at ten springs found many animals that had not been previously recorded from the counties in which they were found. While concentrations of surface contaminants are not enough to threaten the diverse communities of aquatic macroinvertebrates observed in these karst springs, the fact that chemicals from the surface are so pervasive suggests that the potential for harm in the future is significant.
Fragmentation Construction of roads, fields, and houses in previously undeveloped areas destroys habitat, obviously, but the surrounding areas suffer indirect effects that can be nearly as destructive. Once-extensive wetlands, forests, and prairies are fragmented into small habitat "islands." The developed land often becomes a barrier to animals moving between habitats. For example, the American toad often breeds in small isolated patches of wetland but seeks upland woods for the rest of the year. Similarly, timber rattlesnakes find it hard to move from lowland foraging areas to upland rocky retreats where they hibernate; fragmentation is one of the two biggest threats to that species' continued existence in the region, along with indiscriminate killing by fearful humans. The great plains rat snake, a denizen of the Mississippi bluffs from Fults to Renault, is undisturbed within the Fults Hill Prairie Nature Preserve. Many of these snakes, however, are killed by traffic when they attempt to cross the roads that divide their larger habitat, of which the nature preserve is only a part.
Fragmentation not only shrinks habitats, it changes them, as when once-sheltered forest interiors are exposed to drying sun and wind. Probably worse, the entire populations of some plant and animal species in such splintered tracts may include only a few individuals. Populations so small are vulnerable to disease and genetic weaknesses that result from in-breeding. The region in and around the Sinkhole Plain still boasts a handful of sizable forested tracts—the two largest are 1,255 acres each, along the Mississippi and Kaskaskia rivers. However, the mean size of surviving tracts of contiguous forested bottomland is 19 acres, vastly smaller than the 500 acres thought to be the minimum-sized woods capable of sheltering nesting songbirds. The 173 acres of loess hill prairie in the region is split into 12 sites. The more than 3,000 emergent wetlands include a few large ones on the Mississippi near the former site of Valmeyer and near Fults, but the mean size of emergent wetlands is only 4.1 acres.
Hydrology Flood damage costs in and around the Sinkhole Plain are rising faster than the water that causes them. The climate in this part of Illinois is variable, but long-term trends show no marked increase in annual precipitation. Rather, human changes are concentrating runoff from rains and melting snow, making bigger floods out of smaller amounts of water. Building in floodplains is an obvious risk, but paving once-porous surfaces and installing storm drains anywhere in the watershed causes floodwater to collect at discharge points more quickly, making floods higher (if shorter lasting) than ever. A tiled farm field has the same effect as a paved street in speeding the movement of water into nearby streams. Levees also concentrate water in river channels. Minor floods are controlled, but major ones often are made worse.
The lower Kaskaskia River has always tended to flood. Carlyle Lake was built in 1969, 50 miles upstream from the Kaskaskia's confluence with the Mississippi, to catch and hold water that used to overwhelm downstream parts of the valley. The lake has caused noticeable reductions in peak water flow downstream. Carlyle not only lowers flood peaks but boosts flows during droughts when water is released from the reservoir.
Significant parts of some of the region's sub-basins are dominated by mine spoil at the surface. Also, old pits function as de facto wetlands; by storing floodwater, they act as reservoirs that feed water back into streams during dry periods, evening out the flows of streams such as Plum and Doza creeks, whose watersheds have been extensively mined.
In general, however, the remodeling of the watershed in and around the Sinkhole Plain has tended to aggravate the effects of drought. Drained farm fields speed the flow of water into nearby streams. This water used to soak slowly into the soil, building up subsoil moisture that fed streams for weeks or months. As a result, droughts that once merely reduced flow through the region's upland creeks now causes them to dry up completely. In low-water seasons, most of the flow of some streams like Richland Creek is effluent from sewage treatment plants.
Fire Only recently have ecologists realized how important fire was to the evolution of the Illinois landscape. Fires sweeping across exposed prairie helped keep it treeless. (The tender growing points of prairie grasses are located an inch or so below the soil surface, safe from flames.) Occasional fires also shaped the region's presettlement oak-hickory forests, by creating openings in which sun-loving oak seedlings could flourish.
As noted, Native Americans encouraged fires. But Euro-American farmers stopped fires to protect their fields and buildings. Without fires to burn off trees and shrubs, unburned prairies are being squeezed out of existence as woody plants encroach from the forest around them. The Marissa Woods Nature Preserve in St. Clair County may have originally been a savanna that is reverting to forest due to lack of fire. Forests change too. Unburned forest floors have become too shady for oaks, which gradually are being replaced by shade-tolerant maples. In the dry upland forests, in contrast, drought does what absent fires cannot do; it deters moisture-loving interlopers like maples. The rare crested coral-root orchid, a plant of the southern U.S. that is rare in Illinois, is still found in such woods in Randolph and Monroe counties.
Urbanization Managing complex natural systems so as to satisfy the needs of nature is not easy. Managing them to satisfy the needs of humans can be just as difficult. Area farmers disagree with campground operators over how much water to release from Carlyle Lake. The commercial mussel industry complains that barge operators are responsible for its declining catch. Barge operators complain that pleasure boaters in the Kaskaskia River State Fish and Wildlife Area interfere with safe operation of their craft.
No trend poses more complex management challenges than urbanization. Just as the farm replaced forest and prairie, town is replacing farm in parts of the Sinkhole Plain and its environs. Overall human population growth in the larger Sinkhole Plain region—Monroe, St. Clair and Randolph counties—slowed after 1970 with the demise of Metro East's once-busy factory economy. Urbanization continues its spread nonetheless, as population shifts within the region. The Metro East towns of Alton, Belleville, Granite City, and East St. Louis have all lost population since 1990, much of it to small towns nearby. Since 1990, for example, St. Clair County's population rose just 0.4 percent. However, Freeburg, in the once-remote eastern part of the county, has seen a 20 percent increase in population, with 200 new homes being built in a recent three-year period.
Rural Monroe County's population rose 15.5 percent between 1990 and 1998, according to government estimates, and while St. Clair is expected to grow 2 percent by 2020, Monroe County is expected to swell 28 percent. The county seat of Waterloo, a former rural market town, has turned into a bedroom community. Its 7,000 residents live within 30 minutes of downtown St. Louis and 25 minutes from Scott Air Force base, one of the biggest employers in the region. (Waterloo's slogan: "City Conveniences Rural Advantages.") Nearby Columbia is only about 12 miles from downtown St. Louis via Interstate 255. "Columbia is experiencing dramatic growth in recent years," trumpets local boosters, "as former city dwellers discover its peaceful and convenient location." Houses have become the chief industry of such places. Residential property is the biggest part of the property tax base in the region, even in its rural parts; in predominantly agricultural Monroe County it is the source of seven local tax dollars of every ten.
The causes of this population shift are complex, and include cheap land, racial antagonism, and Americans' durable nostalgia for small towns. The region's lifestyle, especially its outdoor recreational amenities, figures in its appeal as well. The region has 340 sizable lakes and many more smaller lakes and ponds. They take many forms—backwater and bottomland lakes, precipitation-filled sinkholes, water-filled pits left by coal mining. It is estimated there are more than 1,500 of these surface waters in Monroe County alone. Such rich opportunities for fish means rich opportunities for anglers. The number of licenses issued suggest that the people of the three counties that make up most of the region—Randolph, St. Clair, and Monroe—have taken to fishing more enthusiastically than other Illinoisans. The same is true of boating.
The State of Illinois maintains five major outdoor recreation sites in the region, and they attract 850,000 visits a year. The most popular is Frank Holten State Park, a golf course and picnicking ground near East St. Louis that was built on reclaimed swampland once known as the Grand Marais. The largest is the Kaskaskia River State Fish and Wildlife Area (SFWA), which extends along 36 miles of the Kaskaskia River from Fayetteville to the Mississippi River. One of the largest state-owned sites of its type in Illinois, it has a land and water area totaling more than 20,000 acres. Some 16,000 acres of mixed bottomland forest of pecan, soft maple, oaks, shellbark hickory, and willow are interspersed with cultivated and fallow fields and patches of native grass and brush. This diversity of habitats nurtures an equally diverse wildlife. About 14,000 acres are open to hunting—from waterfowl to forest game such as squirrel and upland game such as rabbit and quail.
Within the Kaskaskia River State Fish and Wildlife Area is Baldwin Lake. Built by the Illinois Power Company to store cooling water for an electric generating station at the site, the 2,018-acre lake has been leased to the Illinois Department of Natural Resources for recreational purposes. Warmed by its trip through the power plant's pipes, discharged cooling water keeps the lake virtually ice-free year around, allowing fishing in any season. The reservoir is rated a very good spot for bluegill, white bass, catfish, and largemouth bass, the last averaging two pounds.
Peabody-King SFWA is a 2,000-acre site adjacent to the Kaskaskia SFWA. About 90 percent of the site is reclaimed strip mine land donated to the state by Peabody Coal Co. The site has 20 lakes and ponds, and offers hunting for upland game such as doves, which are attracted to the sunflowers grown in several reclaimed fields. Open since 1994, Peabody-King already attracts more than 60,000 visits a year.
The varied landscape of the Sinkhole Plain region also satisfies other outdoor pursuits. Hiking and bird watching are popular, as is bicycling. Several local and state agencies have developed a "greenways" plan for St. Clair, Madison, and Monroe counties that would link new bicycle and pedestrian trails with several current existing regional and national trails, and Monroe County has formed a committee to look into greenspace needs for the future.
As people look to the local land to satisfy more varied needs, a more varied array of landscapes will have to be provided for them. Local efforts already underway to protect the region's remaining presettlement natural systems have promise, but such lands are not plentiful, nor are they appropriate for all such purposes. Restoring damaged natural systems, perhaps even reconstructing destroyed ones, will become important too. Several large tracts of forested land along the Mississippi in Monroe and Randolph counties and the more than 15,000 acres in the Kaskaskia River State Fish and Wildlife Area have potential as breeding grounds for birds that could populate the rest of the region.
Bobcats have been sighted in Randolph and Madison counties since the 1980s, most recently when a road-killed animal was found near Sparta in 1995. Attracting bobcats is a challenge to large-scale eco-management—the cats require extensive and varied terrain and cover—but the Kaskaskia River corridor and the forested bluffs in Monroe County offer suitable habitat. The State of Illinois has been releasing river otters from Louisiana in Illinois river systems, including sites near the Sinkhole Plain. An otter release program in Missouri has shown the animal to be more adaptable than once thought. Apparently they have found Illinois to their liking as well; in 1990 a male was trapped along the Kaskaskia River State Fish and Wildlife Area near New Athens. The Kaskaskia SFWA and Horseshoe Lake are potential habitats for new populations.
All species would benefit from less siltation of surface waters, less pollution from sewage and chemical nutrients, more vegetation along pond and lake edges and streamsides, protected corridors linking existing habitat islands, prescribed burning, and so on. An unknown amount of local land contains degraded natural communities that might be restored to something approaching their original complexity. One example of degraded Sinkhole Plain savanna, for example, lies within the Fults Hill Prairie Nature Preserve, and ecologically degraded prairies also probably persist, still unidentified, on the bluffs bordering the Mississippi and Kaskaskia rivers.
Restoring whole ecosystems is much harder to do than managing healthy ones to favor one or two species. Just as today's physically restored Maeystown looks like, but does not function like, a 19th century town, restored ecosystems may look like their presettlement versions but seldom work like them. For example, a grazed forest, even when left alone, will not revert to its previous ecological identity. Its pre-grazing state can be achieved only through intense management, such as controlled fires to burn off competing plants. Nor is it yet known how all species are affected by induced ecological changes. Restoring a more natural flood pulse to the Mississippi is certain to benefit some species, but it is not clear how it would affect others.
The boundary between natural and human realms, never perfectly drawn, is becoming fuzzier all the time. In natural history terms, nearly half of all the region's land hosts "cultural" communities, meaning plants and animals that inhabit human-created environmental niches such as city streets, farm fields, artificial lakes, and the like. Managing both public and private lands in and around the Sinkhole Plain thus will not be a simple matter of choosing between nature's needs or human needs, but of meeting a wider—and deeper—range of human needs. Beauty as well as building sites, refuge as well as resource extraction are possible, but achieving them all requires land management that is informed by a more complex and sympathetic understanding of natural processes in local settings. It means putting into practice a new principle: what is given to humans does not necessarily have to be taken from nature. ●
Sidebar: A rich history
The Sinkhole Plain and adjacent lands have been home to humans longer than most places in Illinois. Archeologists have surveyed only a fraction of the area, but have found almost 3,000 sites used by humans in every era during their 12,000-year tenure in Illinois. Occupied successively by people of Native American, French, German, and American cultures, the region was the site of the largest North American Indian city, the oldest Euro-American town, the first state capital, and the first Protestant church in Illinois. The past is everywhere in place names such as Cahokia and Kaskaskia, Renault and the Grand Marais (French for "big swamp") Lake, and Millstadt (German for "mill town") and New Hanover.
The best known cave in the region is not really a cave at all. It is the Modoc Rock Shelter, an overhanging sandstone cliff facing the Mississippi between Prairie du Rocher and Modoc. It was used by humans for 6,000 years, beginning in 8000 B.C.
The 2,200-acre tract of Cahokia Mounds State Historic Site, a few miles west of Collinsville, contains the archaeological remnants of the central section of an ancient Indian city that is today known as Cahokia. The city was the center of a network of farm outposts and major satellite towns near the modern communities of Mitchell, Dupo, Lebanon, East St. Louis, and St. Louis. Inhabited from about A.D. 700 to 1400, Cahokia was at its peak between A.D. 1100 and 1200 covering nearly six square miles and home to as many as 20,000 people. It was the largest population center with the most complex social organization and the most influence yet seen in the history of what is now the U.S.
Just as Cahokia dominated the social life of the larger region, the more than 14-acre "Monk's Mound" dominated the landscape of Cahokia. Rising one hundred feet high, Monks Mound is the largest prehistoric earthwork in the western hemisphere. Monks Mound was named for French trappers and monks who lived nearby and gardened on the mound in the early 1800's.
When Euro-Americans arrived, the Sinkhole Plain became the heart of "New France," the farthest flung outpost of France's farthest flung empire. It was settled by traders, missionaries, soldiers, and later farmers who produced fat cargoes of grain for shipment, via New Orleans, to French-controlled islands in the Caribbean. Prairie du Rocher, in Randolph County, was founded in 1722 and is Illinois's oldest town. Near Prairie du Rocher is the reconstructed Fort de Chartres, one of a string of fortified camps built by the French to secure their flimsy empire. The original 1720 wooden fort was destroyed by flood and rebuilt in 1753 with limestone walls 15 feet high and three feet thick.
The architecture of French Illinois survives here and there. The Pierre Menard Home, one of the finer examples of Southern French Colonial architecture built in the "raised cottage" style, offers visitors "the Timeless Charm Of French Colonial Life."
Although some Germans began arriving in the 1830s, most came to southwest Illinois in 1848 after a revolution failed in the old country. Soon there were so many Germans in Belleville that it became known locally as "Dutch Town," a corruption of "Deutsch," or German. Gustavus Koerner was typical in background, if not achievements, of these German emigrants. A political refugee, Koerner came to Belleville in 1833. In Illinois he served as legislator, lieutenant governor, and as state Supreme Court justice. He led an all-German regiment in the Civil War on the Union side, and a grateful President Lincoln appointed him minister to Spain.
The countryside is dotted with German landmarks such as the Holy Cross Lutheran Church of Wartburg, four miles southwest of Waterloo, which was organized in 1841 by settlers from Saxony, Thuringia, and Westfalia. The Gundlach-Grosse Home in Columbia has been placed on the National Register. The town of Hecker, as it is known today, is named for German revolutionist, patriot, orator, and civil war hero, Friedrich Franz Karl Hecker, who reputedly once stayed at a hotel there. Maeystown was founded in 1852 and settled entirely by German immigrants of the revolutionary "Forty-Eighter" movement. The whole of this Monroe County village has been designated a historical district. Sixty buildings dating back to the 1800s still exist and provide a quaint backdrop for a busy calendar of annual festivals.
Even though non-French were banned from north of the Ohio, British subjects began settling in 1779—the lure of land was too great. Most settled in Belle Fountaine, an 18th century settlement located in what is now southern Waterloo. Waterloo is home to the restored Peterstown House, the only intact stagecoach stop along the historic 60-mile Kaskaskia-Cahokia Trail. New Design, one of the area's first settlements, was the site of the first English-speaking school and the first Protestant church in Illinois, both of which are preserved. The town of Red Bud ("The Blossom City") has been recognized as an excellent example of the small 19th century crossroads commercial town, as most of its business district remains architecturally intact. ●
Sidebar: Caves and troglobytes
Some of southwest Illinois's most interesting landscape is underneath the ground—there are 142 known caves in the Sinkhole Plain. Surface water that seeps into limestone bedrock here contains dissolved carbon dioxide, which forms a mild carbonic acid strong enough to eat away the rock. Over thousands of years, passages, chambers, and pits are formed. The best and largest of these "solution caves" in Illinois are located in Monroe County—Fogelpole Cave, Illinois Caverns, Stemler Cave, and, a connected system, Dry Run Cave and Krueger Cave.
Illinois Caverns was marketed as a tourist attraction beginning in 1901 and enjoyed a brief vogue with visitors to the St. Louis World's Fair in 1904. Since 1985 it has been owned and managed by the Illinois Department of Natural Resources. Known in the past as the "Mammoth Cave of Illinois," among other sundry names, Illinois Caverns is big enough to contain its own lakes and streams. Visitors to Illinois's other natural areas must bring their own water or lunch; at Illinois Caverns they must bring their own light, in order to navigate its remote passages. The mineral-rich water that drips and flows in the caverns leaves behind deposits that accumulate in fantastic shapes. The 8,000 or so visitors who traipse along the 14 miles of underground walkways in a typical year can see stalagmites, pillars that rise from the floor, and stalactites, icicle-like formations that hang from the ceiling. Also present are such curiosities as rimstone dams, soda straws, and flowstone, which develops where a thin film of water flows over the walls and floor of a cave, depositing sheets of minerals.
Several Sinkhole Plain caves are protected as Illinois Nature Preserves. The Armin Krueger Speleological Nature Preserve near Burksville in Monroe County is a privately-owned 105-acre site. Fogelpole Cave Nature Preserve, also in Monroe County southeast of Maeystown, is a 27.3-acre state site that protects one of the largest and least disturbed of Illinois's cave systems. Pruitt Sinkhole Nature Preserve in St. Clair County, another private 2.5 acre preserve west of Millstadt, protects several sinkholes that drain into Stemler Cave, the mouth of which is also protected as a nature preserve.
Illinois caves are hospitable to life in many respects. Water is present in most of them, as are minerals, and the air temperature in the deeper ones is a relatively constant 58 degrees F°. Caves however are also dark. While light is the engine of photosynthesis, and thus of life on the surface, the lack of light constrains life below ground. Highly adapted creatures known as troglobytes, or cave-dwelling creatures, manage the trick.
One of these is the Illinois cave amphipod, Gammarus acherondytes, which in the whole world is found only in the caves of the Sinkhole Plain. The Illinois cave amphipod is a small, cave-dwelling crustacean. Less than an inch long and light gray-blue in color, it lives in the "dark zone" of cave streams. There it feeds on dead animals and plants as well as the thin film of bacteria that covers submerged rocks. Like other amphipods, this cold-water species does not tolerate a wide range in water temperatures, is sensitive to touch, and avoids light. This makes it very sensitive to disturbance by human visitors.
The Illinois cave amphipod was recently listed by federal authorities as an endangered species. Historically, it was known from six cave systems within a 10-mile radius of Waterloo. While moderate to small-sized populations persist in Illinois Caverns, Fogelpole Cave, and Krueger-Dry Run Cave, no specimens have been collected in Stemler Cave since 1965, and no specimens were collected in Madonnaville Cave in 1995. Pautler Cave, the sixth known home of the animal, was bulldozed shut by the landowner.
The Illinois cave amphipod is not the only rare creature that finds refuge in Sinkhole Plain caves. Fogelpole Cave shelters more hibernating Indiana bats than any other place in Illinois. The bat is on the federal endangered species list. In summer it roosts beneath the peeling bark of dead trees, a reminder that in a healthy forest even dead trees serve an ecological role. Winters it spends in the stable environment underground, in natural caves and artificial ones in the form of abandoned mines. ●
Sidebar: Varied geology, varied life
Usually geologic formations excite mainly geologists, but the geology in and around the Sinkhole Plain excites a lot of non-scientists as well. In addition to its caves and sinkholes, rocky bluffs abruptly rise 150-200 feet above the Mississippi River in northern St. Clair and southern Madison counties. To see them, visitors come from miles away to take day trips along such scenic drives as the Bluff Road to Maeystown.
Geology can be exciting to residents too, for different reasons. Sinkholes have been known to open up overnight, sometimes beneath roads or buildings. This also is one of the few places in Illinois where rock falls sometimes occur. The region lies close to the seismically active New Madrid fault in Missouri, and more than 100 small to moderate earthquakes—strong enough to crack chimneys—have rattled the region since 1818.
The region's west-facing cliffs offer little to plants beyond extreme drought, highly alkaline soils, intense sunlight, and crevices to root in. Such unusual habitats tend to become homes to unusual communities of living things. At least 25 herbaceous plants are found on the Mississippi bluff faces. So are shrubs such as New Jersey tea, (left) along with vines like the trumpet creeper and nine species of trees. Ten species of fern alone are commonly found in the shadier parts (usually in canyons) of these cliff communities.
Brickey-Gonterman Memorial Hill Prairie Nature Preserve, located on a bluff overlooking the American Bottoms in Monroe County, contains one such high-quality limestone cliff community. Nine plant species considered endangered or threatened in Illinois, such as the wooly buckthorn, are known from these spots. Inhospitable as they are in many ways, cliff communities are also quite fragile. In most parts of Illinois, off-road vehicles are the main threat that recreational use of the countryside poses to nature. Here the hazard to plants is off-road people, in the form of hikers whose boots wear away the soft rock. ●