Southern Illinois the Ozarks of Missouri, is chiefly in southern Jackson, Union, northern Alexander and Johnson counties. The eastern area, more closely related to the Wabash Valley Seismic Zone, is mostly in northern Pope, southern Saline, Gallatin, eastern Johnson and southern Williamson counties. The Shawnee National Forest covers a large territory, including seven wilderness areas: Garden of the Gods, Bay Creek, Clear Springs, Bald Knob, Burden Falls, Lusk Creek, and Panthers Den. Of southern Illinois' rivers, only the Mississippi and the Ohio are navigable for modern commerce. The Big Muddy River, Marys River, Saline River and Cache River run their courses in
Muddy River (Massachusetts) flows through a conduit under Route 9 and into a narrow park called the Riverway, from which it flows through three culverts: the Riverway Culvert, the Brookline Avenue Culvert, and the Avenue Louis Pasteur Culvert. The Muddy River continues from the Fens toward its connection with the Charles River via the Charlesgate area, running through a stone-paved channel surrounded by a narrow strip of parklands. In a series of stone bridges and tunnels, it passes under Boylston Street, Massachusetts Turnpike, Commonwealth Avenue, Storrow Drive, and a series of elevated connecting ramps (the Bowker Overpass). In its natural state, the outlet