Shut-in (river)

A shut-in is an Ozark term for a river that's naturally confined within a deep, narrow channel. The river becomes unnavigable even by canoe due to the rapids and narrow channels produced as the stream encounters a more resistant rock that is more difficult to erode. In the Johnson's Shut-Ins State Park in Missouri hard rhyolite and a diabase dike diverts the stream into many little streamlets following a complex joint system "shutting" the river.