Franklin Creek Nature Preserve

Franklin Creek State Natural Area is located in Lee County, 1 mile northwest of the village of Franklin Grove and 8 miles east of Dixon just north of IL Rt. 38. Beautiful Franklin Creek flows throughout the 882-acre park. Several large natural springs, hardwood forests, bedrock outcroppings and a large variety of flora and fauna comprise a pristine ecosystem. The park contains a 198-acre nature preserve which is an outstanding and diverse natural area in a uniquely beautiful setting. High, rocky bluffs shelter a perennial creek and create an environment rich in flora and fauna. The preserve represents the initial acquisition by the state of Illinois and has been the cornerstone upon which Franklin Creek State Natural Area was built. With its dedication as a nature preserve in 1970, it became Illinois' 24th nature preserve.The geology of Franklin Creek is of considerable interest as the valley is deep enough to expose three distinct rock strata. New Richmond sandstone, a soft rock of Lower Ordovician age, is exposed at the bottom of the gorge. This is the oldest rock formation anywhere in the state, dating back more than 500 million years. Above the New Richmond sandstone lies the Shakopee formation, a sandy dolomite also of Lower Ordovician age. This strata is capped with St. Peter sandstone of Middle Ordovician age and approximately 460 million years old. Away from the outcrops along the creek, which have been exposed by erosion, the bedrock is covered with a deep till from the Wisconsin glaciation. Finally, this is mantled with a layer of loess from which the upland soil developed.The occurrence of vegetation is influenced by soil characteristics, topography and moisture. Low lying areas along the creek bed support a bottomland forest dominated by silver maple and hackberry. Slippery elm and Kentucky coffeetree also occur here. Ravines support mesic (intermediate between wet and dry) upland forest characterized by sugar maple and basswood and paw paw an understory shrub of more southernly distribution. On drier sites, a dry-mesic forest of white oak, red oak, black oak, shagbark hickory and hop hornbeam occurs.A small glacial drift hill prairie remnant is present in the preserve. Indian grass and tall dropseed are characteristic plants of this habitat. Other prairie species present include false toadflax, flowering spurge and hoary puccoon.High quality, undisturbed cliff communities exist on the bedrock outcrops. Canada yew, an evergreen shrub of more northern woods, is common. Bladdernut, bishop’s-cap and shooting star also are found here, as well as several species of ferns.The forested areas provide habitat for many species of nongame wildlife. Woodpeckers, flycatchers, thrushes, vireos and warblers breed on the site. The area provides critical stop-over habitat for many more species during migration. Great blue and green herons have been observed here. Mammals utilizing the area include raccoons chipmunks, gray and fox squirrels, beaver, and deer. Shrews, white-footed mice, weasels and foxes also may be seen. Nineteen species of fish have been recorded from Franklin Creek.