This is called "Appalachian Armoring" and the trail hardening technique was developed by Trail Dynamics, Inc. You'll find this on the south/west end of the Cedar Rock trail. This section of trail was severely eroded before these locust logs were anchored to the soil. Then, slabs of stone (or in this case, broken concrete) are used to "armor" the trail tread (almost like cobblestone paving). This can be used on a section of trail that is too steep to be sustainable, but too difficult to re-route. This should last many years, as locust logs are extremely resistant to rot. An important component of this system is making sure the water is removed from the trail. This is done by digging large rolling grade dips above and below the armored section. And, it is fun to ride!
