Gensburg-Markham Prairie

Description

Gensburg-Markham Prairie is a large natural area consisting of wet-mesic and mesic prairie, dry mesic and mesic sand prairie and sedge meadow communities representative of the Chicago Lake Plain Section of the Northeastern Morainal Natural Division. The Chicago Lake Plain was formed as glacial Lake Chicago receded at the end of the Wisconsinan glaciation. As the water receded, it left behind deposits of clay and sand. The wetlands on the preserve are underlain by clay while the drier sites are underlain by sand. An old beach ridge formed by the ancient lake runs southeast to northeast through the preserve, and is responsible for the difference in relief over the preserve. Gensburg-Markham Prairie is an unusual example of sandy loam prairie; it combines the characteristics of the black silt loam prairies with the true sand prairies. The preserve contains rare plant plant species such as grape fern, sundrop, narrow-leaved sundew and grass pink orchid. In addition, other significant sand prairie plants are colic root, yellow-eyed grass, screwstem and huckleberry. The dominant grasses are big bluestem, Indian grass and prairie dropseed. Typical black loam soil species found here are nodding wild onion, cream wild indigo, prairie coreopsis and prairie alum root. Notable nesting birds include short-billed marsh wren, bobolink, swamp sparrow and Henslow's sparrow.