Flat Rock is another one of Pennsylvania’s beautiful rocky outcroppings that provides some very interesting options. It is actually a summit on its own and guards the south entrance to "Doubling Gap." Located about forty-five minutes west of Harrisburg, and ten minutes north of Carlisle, this summit is well worth a visit. The trailhead for this popular summit is located in the center of Colonel Denning State Park . The actual summit itself is on part of the Blue Ridge. You will not have any trouble finding this place because this is probably the most well marked state park in PA. In seasons where the weather is nice, you can expect to see a fair amount of people on this trail as it is pretty popular.
Geologically, this mountain is similar to that of the South Mountain Group to the south, which you can see from Flat Rock. The rock is a mixture of sandstone and quartzite which provides for some wonderful scrambles on and around the summit. In terms of the view, this summit’s views are comparable to that of The Pinnacle which is a little farther east along the Blue Ridge. As is The Pinnacle , Flat Rock is part of a kink in the ridge. This kink is called “Doubling Gap” because the mountain makes an S-shape which encompasses many square miles.
The hike up this mountain is one of the more strenuous trails in the state, especially in winter time. You will find some slopes on this trail approaching fifty-five degrees in angle. Also, this is only a five mile round-trip hike, but you gain 1,767 feet total. For Pennsylvania standards that is a lot of elevation gain, so do not take this trip lightly. Snow makes it feel a little longer as well.
Views from Flat Rock are just amazing. You have a two hundred degree panorama of the Cumberland Valley. Directly ahead of you to the south is the massive South Mountain Group. To your right (west) you can see the PA Turnpike heading into the mountains. On a clear day, if you look really hard, you can just barely discern the reflection of the Susquehanna River to your left (east). This is a wonderful hike and there is something to be offered to everyone.
Take Interstate 81 South from just north of Harrisburg and head towards Carlisle. Continue past the exits for Carlisle to the exit for PA Route 233 North. Follow Route 233 North for thirteen miles into Colonel Denning State Park . From here there will be signs guiding you to the trailhead. There are also signs marking the exits off of I-81 so don't worry! Enjoy your hike!
This mountain is climbable in all seasons of the year. In summer, spring, and fall you are likely to find a fairly large number of people on this trail. In winter, even though the snow makes it a lot tougher, you'll have plenty of solitude. Winter hikes on this trail are a bit more difficult so do be aware of that. In snow this hike can turn from five miles to eight. Fall is a beautiful time to view the valley below because of the changing leaves. The best time in fall is probably mid-October.
There is no camping along the trail but if camping is what you want to do then you are in luck. Just north of the trailhead there is a tentsite for anyone who wishes. Also, between Buck Ridge and Flat Rock there is a very nice shelter along the Tuscarora Trail. It is first come, first served, but in most cases you will not have too much difficulty.
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Flat Rock Trail This page gives a very brief commentary on the Flat Rock Trail.