From the parking area at the Jawbone Gap trailhead, walk along Crisman Hollow Rd for 100 yards where the blue blazed Gap Creek Trail veers left on a Forestry Service (FS) road. Follow the trail for 50 yards to the first campsite on the left, turn left through the campsite, cross a small footbridge, then begin the assent towards Duncan Knob.
In 1.3 miles, after making several switchbacks, arrive at the intersection of the yellow blazed Scothorn Gap Trail where the blue blazed Gap Creek Trail veers left uphill. Stay straight on the yellow blazed Scothorn Gap Trail as it continues for 1.8 miles to the four way intersection of the orange blazed Massanutten Trail. At this junction, the yellow blazed trail turns right, and the orange blazed trail is directly ahead and turns left uphill.
Stay straight on the orange blazed Massanutten Trail as it descends along Big Run. The trail will descend more steeply before crossing the run for the first time, then re-crossing the run and passing a campsite in 1.7 miles. After passing the campsite, continue to follow the trail for 0.1 miles to the intersection of the white blazed Massanutten Connector Trail.
Turn right uphill staying on the orange blazed Massanutten Trail as it very steeply climbs Waterfall Mountain. The trail will make several switchbacks before reaching the ridge in 0.6 miles from the last intersection. At the ridge, the trail will turn left/south and pass a overlook of the valley before heading more westerly and arriving at Crisman Hollow Rd.
Cross Crisman Hollow Rd, and follow the orange blazed trail as is ascends to the Kerns Mountain ridge. The trail now heads north following the ridge for 4.3 miles, passing several views of both The Knob to the west, and Duncan Knob to the east, before reaching the intersection of the blue blazed Jawbone Gap Trail and the white blazed Overlook Trail.
Follow the out/back white blazed trail for 0.1 miles to a vista of Duncan Knob. Continue on the blue blazed Jawbone Gap Trail as is makes several switchbacks, and descends Kerns Mountain for 0.5 miles where it turns left and joins a FS road. Continue on the FS road for 0.5 miles where the road ends at the intersection of another FS road. Turn right following the blue blazed FS road, shortly passing through a clearing, then returning the Jawbone Gap trailhead in another 0.3 miles.
