Location
St. Peters Village, Warwick Township, Chester County, PA.
Area
15 acres
Drainage
French Creek watershed, directly into French Creek
Geology
Diabase (igneous intrusion)
Stockton Formation (Shale and Sandstone)
(Locally metamorphised at contact with diabase)
Surveyed
August 2002 by Janet Ebert and Jack Holt
Pottstown quad
Site Description
The site is entirely wooded except for the parking lot, the roadside, and the quarry and its banks. The most notable physical feature on the property is the old quarry at the north end. Sheer rock faces, especially to the east and southeast, bar easy access to the deep pool of water at the base except for a narrow path down the west face. South of the quarry the woods slopes steeply down to St. Peters Road. An abandoned narrow-gauge railroad used to haul cut blocks from the quarry runs along the upper edge of the slope, cutting into it in at least two places. Although the rails are gone, taken up for scrap long ago, many of the old ties are still present. East of the railroad cut the woods grows more level, sloping northward towards the quarry.
Quarrying activity ceased approximately thirty years ago, but the operation’s environmental impact still remains. In addition to the pit and the old railroad, piles of spoil litter the surrounding woods, the rusting remains of the crane used to hoist the cut stone out of the quarry sits in the woods near the south face, and the numerous cables used in its operation snake down the rock face into the quarry.
Vegetation
Most of the vegetation of the parking area on the north edge of the property, along the north and west banks and tops of the quarry, and the along verge of St. Peter’s Road consists of weedy alien species of plants. Some interesting natives however are present in these habitats, including a colony of lily-leaved twayblade, an orchid, and an uncommon bush-clover and yellow wild indigo along the road.
In contrast almost all the plants found in the woods are natives, with only a few aliens such as Japanese honeysuckle, bittersweet, stilt-grass, and barberry sneaking in along the edges and trails. The woods shows the striking effect geology, and soil depth, can have on plant communities. In the south and along the steep slope a canopy of oaks and black birch, with hemlock on the steeper slopes, shades an often thick growth of shrubs, all growing on mostly thin acidic soils derived from the Triassic redbed sandstones and shales of the Stockton formation, here altered through contact with the diabase igneous intrusion to the north. Maple-leaved viburnum, blueberries, and huckleberries grow between large stands of mountain laurel, and herbs and ferns are relatively uncommon. Prominent members of the flora here are dittany, a sharp-tasting mint, and spotted wintergreen; the most unusual plant is pink lady-slipper, an orchid.
This community abruptly gives way to the north on a line passing diagonally through the property to a much richer and more diverse herb and shrub flora growing on more basic soils eroded from diabase, marking the change from sedimentary to igneous rock formations. Sugar maple becomes common, oaks less so, and blueberries and their relatives grow scarce. Rich woods plant species found here include black cohosh, horsebalm, and various bedstraws; less common plant species growing here and around the quarry include Virginia snakeroot, woodland joe-pye weed, woodland brome-grass, redbud or judas-tree, and pawpaw. Near St. Peter’s road just south of a roadside parking lot southeast of the quarry is a small shaded seep where a number of wetland species not seen elsewhere on the property grow, including skunk cabbage, jewelweed, and fowl manna-grass.
The woods surrounding the quarry carved into the diabase have grown up since its abandonment. Black birch, sugar maples, and oaks are the common trees to the south and southeast, shading a lush growth of mostly native shrubs threaded together by alien vines and a lush growth of herbs. Close to the edge of the pit the woods in places becomes younger, more open, and weedy. The woods on the bluff east of the quarry are open and dry, with a number of older oaks. The open canopy allows a rich assortment of woodland and upland meadow herbs to thrive here, including numerous members of the bean family, Among the latter is a small population of smooth tick-trefoil (Desmodium laevigatum), a species of concern in Pennsylvania, growing along the trail to the lookout point. The lookout point itself is open and bare of vegetation except for a large specimen of Virginia pine and some grasses and herbs including wild sensitive plant. Below the lookout point the bluff slopes steeply down to the rock faces; the thin scrubby growth of shrubs and vines covering it allows enough sun to permit a healthy assemblage of bean relatives to thrive on the dry sandy soil.
Although a few trees, shrubs, herbs, and grasses survive in cracks and soil pockets on the sheer faces of the quarry, for the most part they are barren bare rock, spoiled in places by graffiti. Except for the aforementioned trail, which leads down to a small bare mudflat littered with styrofoam, the edge of the quarry pond for the most part is steep, rocky, and barren. Several patches of giant reed along the north bank that might harbor other wetland species were not surveyed due to lack of access.
Over two hundred and fifty species of plants, including a state rarity and a number of uncommon species, is a large number to see on a fifteen acre parcel, especially one with a somewhat limited number of habitats and in late summer; doubtless many more remain to be discovered and identified. In addition, both the number and quantity of alien species is quite low for a disturbed tract. This reflects both the quality and variety of habitats present on the land and the underlying geology, as diabase is notorious for supporting a rich and varied assemblage of plants.
Management of the property other than cleanup should be limited to low-impact development of the resources present for recreation, mainly the quarry pond. Any educational or hiking trails through the woods should be limited if possible to already existing ones or the old railroad bed; care should be taken not to disturb the oak-mountain laurel woods and its associated uncommon species if possible. Occasional thinning of the woods in the vicinity of the upper lookout point might also be done to preserve the variety of plant life found there.