Truly a pocket wilderness surrounded by the agrarian Hoosier landscape, Portland Arch Nature Preserve is a 436-acre Nature Conservancy-owned, Indiana Department of Natural Resources-managed property that surrounds the small but dramatic Bear Creek Valley and its namesake arch in Fountain County.
Portland Arch is the only natural bridge in Indiana where a creek flows through. A small tributary of Bear Creek has carved a hole through the soft sandstone lining the canyon to make the unique geological feature.
There are two trails and associated parking areas in the preserve, appropriately marked north and south. The south trail is nearly a mile in length and leads down into the canyon, passing through the arch that is actually located on a small tributary of Bear Creek. After moving through the opening in the Mansfield Sandstone, the well-marked and maintained trail meanders past the foundations of an old dam and into the canyon proper.
One word of caution: while hikers are required to stay on trail while walking in the Preserve, the dam ruins are mere feet off the trail. This invites a detailed inspection and quick clamber over the ruins, but there are numerous deep holes hidden among the forest duff that are just waiting to break the leg of an unwary hiker. There are also several exposed pieces of sharp steel protruding from the concrete.
After moving through the canyon, the trail climbs the ridge top and passes a stand of rare dryland blueberry, wintergreen and black huckleberry. Remember that everything in nature preserves is protected, so resist any temptation of disturbing the plants. In short order, the trail completes its loop and returns you to the parking area.
The south trail passes through the upper end of the canyon but less interesting, much less visited and thus offers more solitude, though it is unlikely that you will be the only visitor in the area if you visit during a weekend.
Both trails are well-maintained but can get muddy due to their path along the creek. Plan accordingly; keeping a second pair of dry shoes in your vehicle is highly recommended in all but the driest weather!
Portland Arch Nature Preserve can be found about five miles south of Attica on U.S. 41. Follow the signs west on county road 650 North.