Dune
The nature of Illinois Beach State Park
Nature of Illinois
Fall 1989
I first visited the dunes lands along Lake Michigan south of Waukegan in the middle 1960s. I doubt I was the only first-time visitor from the cornfields who found the place absorbing. I was grateful therefore when Jane Bolin, my editor at Nature of Illinois, asked if I would spend some time there and make a report.
No place is less like Illinois, and at the same time more typical of it, than Illinois Beach State Park. This stretch of sand dunes and scrub oaks in Lake County is home to cactus rather than corn, a place where strollers are serenaded by surf rather than the rustle of soybeans in the breeze. Yet Illinois's Lake Michigan shore was sculpted and shaped by the same forces—wind and water acting on glacial debris—that made the rest of the state.
Playground and preserve
Illinois Beach today is a combination playground and preserve of more than 4,100 acres to which some 2.5 million people flock annually—far more than visit any other Illinois state park. Illinois Beach is also a vast archaeological ruin. These seven miles of beach and dune are typical of terrain that once lined virtually the whole of modem Illinois' Lake Michigan shore. As lake levels fluctuated over the centuries, the lake built and then abandoned a succession of sand and gravel beaches. Those old beaches survived and today form parallel ridges separated by low-lying swales. Inland, this ridge and swale topography becomes host to dry sand prairies and marshes in turn, while at the water's edge it gives way to low-lying dunes of wind-blown sands.
Illinois Beach has always been a popular spot for excursions and summer homes. Its appeal is partly its exoticism and partly its simplicity. The vistas here consist of sun, sky, and water whose sparseness seems infused by almost Zen-like repose.
Apart from the dunes, Illinois Beach's most distinctive feature is the mile-long Dead River. Dead River belies its name in important respects. It is not a river—it is a narrow pond—and most seasons of the year it is quite lively, being home variously to spawning fish and migratory waterfowl. Dead River does not, however, move very fast or very far. Its outlet into Lake Michigan is usually plugged by a sandbar until backed-up water behind the bar chews through it to send Dead River gushing into the lake. When that happens, the lake immediately begins to pile up sand again like a beaver rushing to cram sticks into a breach in its dam.
Famed landscape designer Jens Jensen championed the preservation of Illinois Beach as early as 1888. Local citizens lobbied in earnest for its designation as a state park in the 1920s, but it was not until 1948 that the section of shore near Dead River was acquired and opened as Illinois Beach State Park. That original parcel was expanded, too, beginning in the 1970s when the state began acquiring miscellaneous properties that comprise what is now known as the north unit of the park, acquisitions that nearly doubled its size.
As a recreational resource, Illinois Beach is unmatched. The park's south unit offers a thousand-foot swimming beach with bath-houses, boating and camping facilities, even a motel-style lodge. The north unit is the site of the 1,500-slip North Point Marina, which will be the largest on Lake Michigan when it is completed in April of 1990.
Downcoast from the lodge, the park is devoted to more passive pursuits. A nature area is open to the public, some half-million of whom hike, sunbathe, or go birding along the beach, among the dunes, or on the four miles of trails (equipped with lookout platforms and interpretive stations) provided by the state's Department of Conservation. The southernmost 1,100 acres of the site were officially designated a nature preserve in 1964—the first such site in the U.S., according to site superintendent Bob Grosso. That tract is reserved for research and is accessible only by permit.
Exotic Illinois
As many as 60 plants and animals recognized as threatened or endangered in Illinois may find refuge at Illinois Beach. No fewer than 16 natural community types are represented here, from the dune face to ponds to savannah-like open woods. It is not only Illinois's most exotic natural place, but also perhaps its most varied. Birds of the farm field such as the Eastern bluebird nest just yards from where shore birds such as the piping plover stop to feed, and fen-loving plants such as the fringed gentian grow only yards away from interlopers from the arid West like the prickly pear.
A walk inland from the shore is a quick course in natural plant succession that ends in the climax community of the scrub oak forest. The sandy soil of these ancient beaches is an inhospitable habitat for a tree, the more so since these Hill's oaks and black oaks must endure not only drought and wind but fire. Park staff burn the nature areas every three years as part of their management plan, mimicking the natural prairie fires that regularly burned off undergrowth and saplings of more fragile competitive tree species. Oaks typically dominate these open savannahs, explains Ken Robertson, botanist in the Illinois Natural History Survey's Center for Biodiversity, because they do well in surviving fire. (Among the other species that do well in spite of the burning, jokes superintendent Grosso, are the mosquitoes and the poison ivy.) The result is twisted trees that are the antithesis of the majestic oaks familiar from more clement corners of the state. Some of the oaks in the Illinois Beach scrub forest are known to be at least a century old, yet have only attained heights that many a yard tree reaches in a tenth of that span.
Indeed, for all its seeming delicacy, Illinois Beach offers some brutal environments for living things in the state. A beach may be a sublime habitat for the human animal on a balmy day, but for a plant it is a hell of pounding waves, scalding sun, and wind. Even on the foredune, immediately inland from the shore, few plants can survive, much less thrive. The plant pioneers that homestead on these treacherous frontiers are a hardy bunch—beach pea, common bugseed, sand reed, seaside spurge, marram grass.
The interdunal plant environments are less punishing, and membership in those communities is more numerous. Two conspicuous members of the inhabitants of this niche are the creeping juniper (a shrub that is more branch than leaf) and the bearberry. In the poorly drained terrain typical of a post-glacial landscape, differences in elevation as small as one foot can make big differences in soil moisture and thus in the roster of species. The results are sometimes anomalous. The sandy soil may look like a desert, but water is usually only feet away, in underground formations saturated by the nearby lake. Some dunes grasses send roots down ten feet; so do the cottonwood trees that thrive in the park, trees that usually are found huddled in Illinois's moist stream bottoms.
Few of these plants are rare outside Illinois, says Robertson. Most are so common on the coastal plains of the eastern U.S. that the only thing a botanist from Cape Cod would find strange here would be the accents of his Illinois hosts. What is rare is the variety of habitats. The nature preserve proper, reports Robertson, astounds even first-time botanizers familiar with the rest of the park, who find a "markedly different world down there."
The diversity of life in all groups is immense. Plant species so far identified within the park number in the hundreds. "It's always been a place for Natural History Survey staff to collect," notes Dr. Warren Brigham, director of the Center for Biogeographic Information. "Dead River in particular has often turned out to be the place from which new species are described." Not just species new to Illinois, but new to science, as was the case with the aquatic beetle collected by Brigham in the 1970s. Ecologically, Illinois Beach is an outpost of species whose ranges are centered to the east, north, and west. It is this overlapping of ranges that explains what Brigham calls the "phenomenal" richness of life along the shore.
Lake Michigan as architect
While harsh, the dunes environment is inherently fragile. The active dunes that line the shore are made up of what the geologists poetically call Aeolian sands, after the Greek god of wind. The lake winds constantly nibble at the dunes. Where a dune's flank is left unprotected by plants, even light winds can lift the sand by the bucketful, leaving hollows known as blow-outs. (Some visitors have found that blow-outs are ready-made sunbathing booths.)
The near shore in particular is forever being redefined. A storm can flatten a dune overnight, only to rebuild it again over the following weeks and months. In this way a dune may disappear but the dunes persist. Such changes can be inferred from the nature and sequence of the sediments left behind by the lake. Where the botanist sees habitat, in other words, the geologist sees a history book. Ardith Hansel, geologist with the Illinois Geological Survey's Quaternary Framework Studies Section, is part of the team that is studying core samples and other data from this beach record. (Among the preliminary findings: The beach remnants that cover today's shore plain are no older than 3,000 years.) Illinois Beach is particularly valuable, says Hansel, because, "It's the one area in Illinois where you can access the Late Holocene lake record. It's an opportunity to study changes through time."
Such investigations see into the future as well as the past. Charting the cycles of Lake Michigan's rise and fall will help public policy makers anticipate shore protection needs. "We're trying to determine what lake level fluctuations have been like," explains Hansel, "to ascertain if the short, 90-year historical record is a good analog for the past 4,000 years or so."
Lake Michigan is a fussy architect, forever fiddling with its designs. Waves constantly chew away sands and gravels from one spot of the shore and move them to another, eroding one section of shore while it builds another. This endless redrawing of the shoreline can be inconvenient to humans. Housing subdivisions, even whole villages, once stood off the town of Winthrop Harbor near the north unit in what is now several feet of water.
During 1985–86, when the lake levels stood at record highs, the shore along the north unit was receding at a rate of 80 feet a year. For a while, in fact, there was no beach at Illinois Beach. During those fretful months, storm waves would overtop the foredunes, crashing into the swales behind them like soldiers swarming into the enemy's trenches. "We never had interdunal ponding before," recalls superintendent Grosso. Plant communities that quickly responded to the damper regime offered a perfect laboratory of plant adaptation, but the lake dropped precipitously before a field study could be mounted, leaving both the plants and the scientists high and dry.
How Lake Michigan goes about making and remaking its shore is a puzzle that has long fascinated researchers at the Geological Survey. Chief among them is Charles Collinson who after nearly 18 years of study is regarded as the guru of Illinois lake watchers. During a high-water phase in the mid-1970s the old Stratigraphy and Surficial Geology Section maintained a field research station at Illinois Beach, which offers one of the longest stretches of unarmored, untampered with shore left on the Illinois side.
Oasis and commerce
What the lake destroys, however, it usually rebuilds. The graver threats to the Illinois lake shore above Chicago have always come from land. The area's natural advantages—its scenic appeal, its easy access to shipping and lake water, its proximity to major population centers—have always been exploitable as economic advantages as well. Often these commercial intrusions were benign; in the nature trails today one can see the relic stone piers from a narrow gauge railway that used to carry ice cut from the Dead River to nearby Waukegan. Today the site is ringed by factory sites, housing developments, and power plants. That splendid sense of isolation one feels inside parts of the park is only an illusion. Construction just outside the park boundaries has changed water regimes inside the park, although not yet significantly, and a sentry line of monitor wells stands guard in case waste from an asbestos dump on adjacent property seeps into the park's aquifers.
Barring such unhappy intrusions, Illinois Beach State Park will survive as a place where one can leave Illinois without having to leave it. As Ken Robertson says, "It's a markedly different world." ●
