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Field & Street



We parked our car in a lot at the eastern end of the Waterfall Glen Forest Preserve and started walking west through a stand of red pines. The Chicago area is not famous for red pines, and these, all the same age and size, planted in neat rows, strongly suggested the involvement of the Civilian Conservation Corps. I don't know for sure that they planted this little patch of artificial forest, but I know they planted a lot like it.

The CCC was a wonderful enterprise. It gave tens of thousands of young men of the Depression era a chance to make a few dollars doing healthy, outdoor work, but some of its conservation decisions seem a little weird in retrospect. Of course if we were faced with abandoned, rapidly eroding land and nothing available to save it beyond some strong backs and a lot of pine seedlings, we might do the same thing.

Our goal was to reach the Poverty Savanna, miles away at the western edge of the preserve. The savanna is a large ecological restoration project under the direction of the Forest Preserve District of Du Page County. I think there is a way to drive very near to it, but my wife, Glenda, and I were looking for a nice hike, so taking the long way in seemed like a good idea. Along the way we encountered all sorts of interesting landscapes, natural and otherwise, that told many stories about the past and present of this land.

Just past the pines was a small piece of ground dominated by scattered large oaks. You can find big trees like these in almost any forest preserve in the Chicago area. They stand like giants amid the slender trunks of young ashes, maples, box elders, and black cherries. They are always oaks. Most commonly, they are white oaks, although bur oaks, swamp white oaks, and red oaks show up from time to time. The size of them all sets them apart, and so does their shape. Their crowns are broad. Often the trees are as wide as they are tall. Dead limbs, their bark long since rotted away, extend out from the lower portions of the trunks.

The first of these giants along our footpath was surrounded by a dense resprout of common buckthorn. This pestiferous European plant--it is, depending on how you define it, either a small tree or a tall shrub--has practically taken over many natural areas. Cut one stem, and ten will grow in its place. Somebody may have cut some buckthorn in this place. The resprouts were young. The slender stems were three to four feet tall, the right size to substitute for wicker in lawn furniture.

The Waterfall Glen preserve forms a large trapezoid that surrounds the Argonne National Laboratory at the southern edge of Du Page County. The northern boundary is just south of I-55. The southern border is the Des Plaines River. Our parking lot was at the southeastern edge of the preserve. The Poverty Savanna is near the southwestern corner. Our walk would take us across the southern portion of the preserve where the land slopes sharply down toward the Des Plaines.

About 14,000 years ago a proglacial lake called Lake Chicago, the ancestor of Lake Michigan, was dammed between the ice front and the Valparaiso Moraine, the huge system of morainal lands that extends south from Lake and McHenry counties through western Cook and eastern Du Page counties and then swings east through northern Will County into Indiana. Fed by the melting ice, the lake got deeper and deeper, until it overtopped the moraine in what is now southwestern Cook County. An enormous flood poured through the new opening, scouring a channel a mile wide and a hundred feet deep in the loose glacial till of the moraine. The cutting stopped at bedrock. Today the placid little Des Plaines--along with the Sanitary and Ship Canal--flows through the deep valley cut by the torrent. There are a few places along the trails we walked where you can look across the valley at the town of Lemont and the glacial hills that rise behind it.

Our hike took us along the northern slope of the valley. We crossed several streams that flow south off the moraine to the Des Plaines. The largest was Sawmill Creek, a stream large enough to have cut a substantial valley of its own. Big sycamores and American elms grew in that valley, both trees typical of floodplain forests. There are actually places along Sawmill Creek where you can stand on a bluff and look down 30 feet or more to the creek and the big sycamores that grow on its banks. You could almost imagine you were in the Ozarks--if you didn't notice that the bluffs were made of glacial till and not sandstone.

There is a dam on the creek that looks very much like a CCC project. It was built of huge pieces of flagstone, and from a distance you could almost take it for a natural feature. For long stretches the trail takes you through land that was stripped of its natural vegetation long ago. Moving in to fill the vacancy are more buckthorns than you would care to count and a virtual carpet of garlic mustard. Garlic mustard is another import--an accidental one. It has spread through Illinois in the past few decades, occupying both upland and floodplain woods, almost to the exclusion of any native herbs. But here and there, even in the worst of this stuff, the occasional giant old oak rises up. Like a Mayan pyramid buried in rank jungle growth, these old trees speak of glorious times in the past. Their new leaves speak of hope for the future.

We passed some actual human ruins too. I don't know who built them. There was a small concrete building with its roof long since gone and a tree growing where its floor had been. Low flagstone walls extended out from the building into the woods on either side. On the lintel of the only door was an inscription: LPS.1921. I suppose the initials could stand for a company name and the numbers could be the date the building was erected, but I prefer to think the inscription should be read "LPS dot 1921."--an E-mail address left by extraterrestrials.

I spent some of the time comparing the undersides of maple leaves. We have in this region two very similar species of maples, the sugar maple and the black maple. Or at least that is what most scientists think. Some believe that the putative two species are actually just two varieties of sugar maple. The leaves are supposed to be the most readily detectable difference between the two. Sugar maple leaves are supposed to be five-lobed, while black maple leaves are three-lobed. Black maple leaves are supposed to be hairy on their undersides, especially along the midrib, while sugar maples are smooth.

Most of the leaves I looked at were plainly five-lobed and also quite hairy. This blending of characteristics is quite common, and it may be a product of changes in the landscape since settlement. The sugar maple is a very fire-sensitive species. In presettlement times fires were quite common. Sugar maples could live only in the few places where the topography kept out fires. Black maples lived in open forests with red oaks and other fire-resistant species. Fire was probably the sorting agent that kept these species separate. With fire largely removed from the landscape, these two species could grow in the same places. Crosses could be produced that would blur the identities of Acer nigrum and Acer saccharum. Now that land managers are once again introducing fire to the landscape, black and sugar maples might again go their separate ways.

We saw a few patches of rich blue woodland phlox along the path, and the occasional catbird mewed from the buckthorn thickets. But we didn't find much that had any natural interest until we neared the western end of the preserve. Our path, which had apparently once been a road, looked out over the valley to the south. To the north the land sloped upward toward the top of the moraine through forests choked with buckthorn. And then, all of a sudden, the buckthorn was gone. The forest looked open. We could see a long way up the slope. Garlic mustard was present, but it grew as scattered individuals and small clumps, almost as if it belonged in this community.

My plant-identification skills are rather rudimentary. I almost always need a flower to help me put a name on a strange plant. A few of the early spring wildflowers--spring beauty, cut-leaved toothwort, red trillium--were still around. Jack-in-the-pulpits were in full and glorious bloom. Wild geranium leaves seemed everywhere, but all the flowers we saw were on plants growing on the slopes of the small ravines that crossed the land. Scorched bark on some of the trees showed that this area had been burned in recent years. The ravine slopes may have escaped the fire. Perhaps fire was once again acting as the sorting agent on this landscape.

Shooting stars were in bloom too. These lovely flowers grow on prairies and in open woods. Dense forests, the kind that grow in the absence of fire, are too dark for them.

We could only guess at many of the species. Perhaps we saw nodding trillium, and possibly we saw joe-pye weed among the many plants that were just beginning their season's growth. The dark green patches of grass could have been woodland brome. The pale green sedges were mysteries to us. One of the major differences between the native open woodlands of this region and the dense forests of the east is the amount of light reaching the forest floor. In the shady dense forests most wildflowers bloom early in the season before the trees are fully leafed out. In the open woods enough light reaches the ground to promote the growth of wildflowers throughout the summer. We could come back here in July and again in August and learn the identities of many of these mystery species.

We followed the winding trail through this lovely open woodland until we reached the most startling sight of the day: a patch of real, open savanna. This is the parklike landscape that early settlers found so strikingly beautiful. This is where those huge, wide-crowned oaks live. This is the context for them, the place where they fit in the landscape. As if on cue, a red-headed woodpecker, exactly the sort of the bird that is supposed to live in this kind of place, flew up from the ground and landed on an oak limb. It had been worth the walk.

You can visit Waterfall Glen by taking I-55 to the Cass Avenue exit and going south. Signs will direct you to parking areas, where maps are posted. The trails we walked are multipurpose. Both bikes and horses can use them.

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