The most prominent natural features of Raven Glen are Timber Lake, which is a glacial lake, Hastings Creek, scattered wetlands and rolling terrain with oak and hickory groves.
With a sandy base, Timber Lake supports the population of rare Iowa darter fish. Fishing is allowed at Timber Lake, but not at White Slough. While the Forest Preserve owns 95 percent of Timber Lake, the northern portion of the lake is privately owned and not accessible for public use.
Ongoing restoration of Raven Glen's savanna, prairie, wetlands and streams enhances the water quality of Timber Lake. It also improves habitat for wildlife, including grassland bird species like the eastern meadowlark and bobolink, and wetland birds such as great blue herons, egrets and other waterfowl.