Woodman Hollow State Preserve is located in the Des Moines Lobe landform region and contains a wooded ravine with layered sandstone cliffs. A stream runs through the deep canyon and eventually leads to the Des Moines River at its eastern boundary. A spring in the western boundary feeds the stream and which, during periods of heavy rainfall, forms a 12 foot waterfall. The preserve contains 2 prehistoric rock shelters with evidence of Woodland Indian and possibly Archaic Indian habituation. Also on the preserve are structures built by the Civilian Conservation Corps, including a concrete bridge foundation and two latrines. More than 500 plants grow here, including 13 ferns and 142 mosses, liverworts and hornworts. The forests are occupied mainly by white oak and red oak in the dry uplands and in the moist slopes, basswood and black maple. March brings blooms like snow trillium, bloodroot and hepatica. June welcomes flowers like bracted orchid and wild sarsaparilla and fall comes with forbs like Ontario aster and spotted jewelweed. Various ferns also grow in the woodlands. The north rim of the canyon features small prairie openings, which house grasses like big and little bluestem. Wildflowers like golden alexanders and pale purple coneflower appear here in April and May. The summer months of July and August welcome blooms like thimbleweed and showy tick-trefoil.

The Woodman family sold the Board of Conservation the property in 1927, and it became an archaeological, biological and geological state preserve in 1970.