After the Ice Age 20,000 years ago, Sagawau Canyon's 40-foot deep dolomite limestone walls were cut from a small, clear, cold water creek running through its center. Now, Sagawau Canyon is the Chicago Metro Area's only canyon containing numerous species of flora and fauna found only in this well-protected and very fragile ecosystem. The limestone walls of the canyon is estimated to be over 400 million years old.

Above ground at the Sagawau Canyon Nature Preserve is dedicated Bird Sanctuary that annually counts about 140 different species of native and migratory birds.