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
Vermilion River (Illinois River) Vermilion River (Illinois River) The Vermilion River is a tributary of the Illinois River in the state of Illinois, United States. The river flows north, in contrast to a second Vermilion River in Illinois, which flows south to the Wabash River. The Illinois and Wabash rivers each have a tributary named the Little Vermilion River as well. The north-flowing Vermilion River and the south-flowing Middle Fork Vermilion River run on what is close to a straight line between Oglesby and Danville. In presettlement times, the two rivers drained an upland marsh near Roberts. It is possible that early settlers regarded