Tideman Johnson Natural Area was created in 1940.
The area of Tideman Johnson Natural Area is 31,120.325888256004 square meters.
The area of Johnson Run Natural Area is 874,120.9872384 square meters.
The Channels Natural Area Preserve was created in 2008.
Snyder Middleswarth Natural Area was created in 1921.
Tandy Hills Natural Area was created in 1987.
Volo Bog State Natural Area was created in 1970.
Union Bay Natural Area was created in 1972.
Dukes Research Natural Area was created in 1974.
Sielbeck Forest Natural Area was created in 1998.
Hill Country State Natural Area was created in 1984.
Cornwall Area of Outstanding Natural Beauty was created in 1959.
Spitler Woods State Natural Area was created in 1937.