Big Walnut Natural Preserve is a scenic 2,600 acres among the rolling hills and steep ravines of Big Walnut Creek Valley. Within it is the Hall Woods Nature Preserve and two distinct trails.
Predominantly a mesic upland forest with lowland or floodplain forest occasionally interspersed along many ravines, the lowland species that thrive here include silver maple, sycamore, buckeye and tulip trees. In the more mesic upland areas sugar maple, white oak, hickory, white ash, and cherry trees are dominant. A noteworthy feature in the upland forest is the very high frequency of large white oak. There is also a thick understory where many specimens of sassafras, dogwood, beech, and spicebush can be found.
Hall Woods Nature Preserve, within the larger Big Walnut Natural Area, is a Registered National Natural Landmark. Big Walnut has been identified as among the best quality stream segments in Indiana. Portions also contain fine stands of old-growth trees. More info is here.
The Hemlock Ridge Trail contains high quality examples of mesic floodplain, upland and ravine forest communities. It also contains a stand of eastern hemlock, a rare conifer more commonly found much farther north.