Green River Lowlands ​ COA

Located within the largest natural division of Illinois — the Grand Prairie — and formerly covered by the Wisconsin Ice Sheet, the Grand Prairie Division is marked and surrounded by a system of moraines. Immediately adjacent to the Bloomington moraine lies a glacial outwash plain known as the Green River Lowlands. Parts of both landforms are incorporated into the COA. These two landforms are quite dissimilar and reflect the geological diversity of the COA. Sand blowouts are a prominent feature; where these depressions overlie impermeable strata they contain ephemeral wetlands hosting an interesting and diverse biota adapted to this vanishing habitat type.
 
Standing in sharp contrast to its dune topography are the Green River Lowlands, once dominated by Inlet Swamp and the Great Winnebago Swamp. Now correctly recognized as prairie 

 marshes, these immense wetlands covered hundreds of thousand of acres pre-European settlement, with black oak savannas interspersed on low dunes. While post-settlement activities such as drainage and cultivation have greatly altered lands in the Green River COA, this COA is especially rich in herpetological resources including ornate box turtles, Blanding’s turtles, and the legless glass lizard.  Several large parcels have permanent protection such as the 2,565-acre Green River State Wildlife Area. Quality protected natural areas including the Ryan Wetland and the Sand Prairie Land & Water Reserve; Foley Prairie Illinois Nature Preserve; Illinois Audubon Amboy Marsh Nature Preserve and IAS Gremel Wildlife Sanctuary. Uncommon plants such as tubercled orchid and queen of the prairie exist in the Green River COA, as do regal fritillary butterflies and rare dragonflies.