According to Exploring the Land and Rocks of Southern Illinois by Stanley E. Harris, Jr., C. William Horrell and Daniel Irwin, the Shawnee Hills Division is explained in the following:
My non-technical description is that the Shawnee Hills are an undulating landscape roughly located below Route 13 extending to the wetlands of the most southern tip of Illinois. It is a land composed of sandstone bluff vistas and tumbling seasonal waterfalls. In this area our own form of hoodoos located at the Garden of the Gods reside and hidden fractured rock have created inspiring natural bridges.
Most important of all it is the place that I can home.