Rock Hollow Trail is a 2.3-mile multi-use asphalt trail in the 252-acre Rock Hollow open space park, managed and leased by the City of Wildwood from Saint Louis County Department of Parks and Great Rivers Greenway, adjoining Castlewood State Park and connecting to the Al Foster Memorial Trail. The trail follows the old Lawler Ford Road route, a road whose name has an obscure origin but which appears on maps from the mid-1860s, before a bridge crossed the Meramec River, when it ended at a ford used by travelers crossing the river; in more recent times, trucks hauling sand and gravel mined from the Meramec River Valley used the road. Rock Hollow is a small, two-mile-long watershed that drops more than 300 feet from the uplands to the Meramec River, where wind, weather, and a small creek carved a steep valley over immense spans of time. Its rocks are entirely sedimentary, deposited in shallow oceans between 300 and 500 million years ago, and fossils such as crinoids, seashells, and coral record that watery origin. Large outcroppings of dolomite, with layers of sandstone between them, form shelves and cliffs that create micro-habitats for ferns, mosses, and lichens, while groundwater moving along horizontal rock strata emerges as numerous seeps and seasonal springs. The park contains several distinct natural communities shaped by slope, moisture, soil depth, and topography, and a Missouri Native Plant Society field study found more than 319 plant species, more than 12 fern species, and 43 moss species there. Rocky south- and west-facing slopes support glade plants and stands of Eastern Red Cedar, while deeper soils lower in the valley support lush growth and bottomland woodland with Kentucky Coffeetree, White Ash, Shellbark Hickory, Bur Oak, Ohio Buckeye, Spicebush, and Paw Paw. The Meramec Greenway was established in 1975 to plan and coordinate recovery of 108 miles of the lower Meramec River after years of abuse and neglect, and the Meramec River Recreation Association, made up of governments with jurisdictions on the river and area citizens, led the restoration as water quality improved, the river setting recovered, and more than 28,000 acres of public parks and conservation areas became available.