Sourland Mountain Preserve Loop


This hike loops around this Somerset County park, passing through several interesting boulder fields.

3 hours
Easy to Moderate
5.6 miles
Route Type:
Allowed on leash
First Published:

Daniel Chazin



View Sourland Mountain Preserve in a larger map

Trailhead GPS Coordinates
Driving Directions

Take I-80 west to Exit 43 and proceed south on I-287. Take Exit 17 and continue south on US 206 for about 7.6 miles. Turn right onto Amwell Road (County 514) (do not turn right at New Amwell Road) and proceed for 2.8 miles to East Mountain Road. Turn left onto East Mountain Road and follow it for 1.9 miles to the entrance to Sourland Mountain Preserve, on the right. GPS address: 415 East Mountain Road, Hillsborough, NJ 08844.


Sourland Mountain is a ridge which straddles the borders of Somerset, Hunterdon and Mercer Counties. Due to the harshness of the land and its unsuitability for farming, large portions of the ridge have remained undeveloped. The largest protected portion of the ridge is in Somerset County, where about 3,000 acres have been set aside as a preserve, administered by the Somerset County Park Commission.

The preserve offers three loop trails, marked with white blazes with the logo of the Somerset County Park Commission. The white-triangle-blazed Maple Flats Trail and the white-circle-blazed Pondside Trail are short, easy loop hikes. The five-mile-long white-square-blazed Ridge Trail is more challenging, and it permits one to spend several hours exploring this beautiful preserve. In addition, trails blazed with red circles and red squares connect with the Ridge Trail and extend into adjacent private property. Finally, there are several short connecting trails, marked with "C" blazes on a white background. This hike follows the Ridge Trail and the Red Circle Trail (none of the short connecting trails are included in the route of this hike).

From the kiosk at the edge of the parking area (trail maps of the preserve are usually available here), head west across a grassy field. At the edge of the woods, you will notice a wooden post with three blazes - white triangle, white circle and white square. This marks the start of the three loop trails, which head uphill into the woods, paralleling a brook to the left.

Follow the joint trails for about five minutes until you reach post #1 (all intersections are marked with white-on-green reflective numbers on wooden posts). Here the white-triangle and white-circle trails turn left, crossing the stream on a footbridge, but you should continue ahead on the white-square-blazed Ridge Trail.

The white-square-blazed trail proceeds steadily uphill (you'll climb a total of about 400 vertical feet during the first part of the hike), skirting a small boulder field. It goes through a heavily wooded area, far removed from the homes and farms that you passed on your way to the park.

After about 15 minutes of steady climbing, the trail levels off. Soon, after another short climb, you'll come to an area of huge boulders. The first gigantic boulder is just to the left of the trail, but you'll encounter many other large boulders in the next half hour or so. This is the most interesting part of the hike, so take your time to enjoy the unusual boulders. At one point, the trail goes through a narrow passage between two huge boulders. Towards the end of the boulder field, be alert for another unique feature of this trail - a large tree that has grown out of a horizontal crack in a boulder!

The trail continues through a forest that features many tulip trees - tall, straight trees, with no branches below the treetops. You'll notice a number of multiple tulip tree trunks growing out of the same roots.

Finally, after about an hour of hiking, you'll reach post #4. To the left, a connecting trail leads back towards the parking area, but you should bear right to continue along the white-square-blazed trail. In another 200 feet, you'll come to another junction. Here, the white-square-blazed trail bears left, but you should turn right onto the Red Circle Trail, which proceeds through another boulder field, climbing gently.

In about 15 minutes, you'll pass through a gap in a chain-link fence and enter the private property of the 3M Company. The company has permitted the trail to be routed through its property, but hikers are requested to remain on the trail. In a short distance, the trail crosses the Texas Eastern gas pipeline.

Soon, the trail winds through another boulder field, passing a number of interesting huge boulders. For much of the way, the trail route is relatively level, but it eventually descends a little.

After following the Red Circle Trail for about 45 minutes, you'll reach a junction where a connecting trail (marked by "C" blazes) begins on the left. You should bear right to continue on the Red Circle Trail, which soon begins a steady descent towards Roaring Brook. Just before reaching the brook, the Red Square Trail joins from the left. Continue ahead, now following both red circle and red square blazes, with Roaring Brook directly to your right. The trail continues to descend, parallel to the brook.

In a short distance, you'll reach a junction marked by post #7 and a huge cairn. Here, you'll rejoin the white-square-blazed Ridge Trail, which comes in from the left. Continue ahead, now following the route of three trails - Ridge, Red Circle and Red Square.

In about five minutes, you'll go through a gap in another chain-link fence and reenter Sourland Mountain Preserve. Just beyond the fence, you'll notice post #8. A connecting trail (marked by "C" blazes) goes off to the left, but you should bear right to continue on the white-square-blazed Ridge Trail (the Red Circle and Red Square Trails end here). Soon, the white-square blazes bear left and head away from Roaring Brook.

In another 15 minutes, you'll cross a boardwalk over a stream and pass an old stone-and-concrete wall (possibly built as a dam) to the left of the trail. Just beyond, you'll come to a four-way intersection marked by post #9, where you should continue straight ahead.

The next stretch of trail is nearly level, and it features a long boardwalk and many short stretches of boardwalk. In another 20 minutes or so, you'll reach post #10. Here, you'll encounter the white-triangle-blazed Maple Flats Trail once more. Turn right and follow both white-square and white-triangle blazes, soon crossing another long section of boardwalk.

A short distance beyond, you'll again cross the gas pipeline (marked by post #11). Continue straight ahead, soon reaching post #12, where the white-circle-blazed Pondside Trail joins from the left. Here, you should turn right, now following all three trails - white triangle, white circle and white square. Soon, you'll emerge onto a grassy area and descend towards a small pond. Bear left around the pond, pass post #13, and you'll reach the parking area where the hike began.

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Sourland Preserve Loop Hike

I did the loop on Memorial Day (hot humid) - an interesting trail but not among my top-ten in the state. The Devil's Half Acre is cool and worth the trek. Pictures from my hike at Sourland Preserve - For me, I did not find Rolling Rocks all that exciting -but perhaps after a major rain storm or winter thaw.... and as noted before - From #6 you can take the Red Square to the Rocks -then continue up to #8.


It is now permissible to cross through the fencing to see the huge boulders around Roaring Brook. This arrangement was made with 3M Company some time ago. My source for this is Sgt. Phil Richards of the Somerset County Park Rangers. I call Phil from the trail all the time about downed trees, whatever. This park is close to home for me, so I hike it frequently. I highly recommend hiking the big trail, the Ridge Trail, with the square blazes, backwards, clockwise, 13 to 1. That way, the long walk in from 13-9 is a good warm up. If you hike 1-13, from 9-13 is just a long, often wet, slog out. With the boulders, boulder field at the brook. and incredibly thick foliage, Sourland comes close to rivaling some Highlands area hikes. Don't miss it.