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How To Build Natural Rock-Climbing Anchors Using Rocks and Trees

You’ve just finished climbing a tough pitch. Relieved, you pull onto a big belay ledge—only to find that the cracks have run out.

You look high and low, but there’s nowhere to place a cam or even the smallest stopper. In such a scenario, all your traditional anchor-building tricks become suddenly useless. That’s when it’s time to get creative. 

Boulders, trees, and even horns and holes in the rock are all valuable sources of protection, or “pro,” in single-pitch and multi-pitch scenarios alike. When you build an anchor using these features, it’s called a “natural anchor.” Here are a few of the most common methods for building one. 

Three Ways To Sling a Tree 

We’ll start with a quick caveat: Slinging a big tree is often a safe and simple way to build an anchor, but it shouldn’t necessarily be your first choice. Over time, abrasion from ropes and webbing can destroy bark, which will eventually kill the tree. That said, sometimes there’s just no other option. In that case, consider that big ol’ pine fair game. Here’s three ways to sling it.

To practice these methods, you’ll need:

  • 25 feet of 7 mm cordelette tied into a loop with a double fisherman’s knot
  • A 60- or 70-meter climbing rope 
  • 10 meters of static line 
  • A Prusik loop or an assisted-braking device like a GriGri 
  • Three locking carabiners

The Figure-Eight on a Bight 

This is a great all-purpose trick. It’s suitable for building either multi-pitch or top-rope anchors, or for using trees as protection while leading.  

  1. Throw your cordelette loop (or webbing sling if the tree is small enough) around the base of the trunk. Make sure the fisherman’s knot (or webbing bartack) is behind the trunk and out of the way.
  2. Pull the ends of the cordelette toward you until they’re even. Lay them atop one another. 
  3. Tie a figure-eight on a bight, incorporating all strands in the knot. 
  4. The resulting two-stranded loop is your masterpoint. Clip a locking carabiner here for your personal tether. 

The Bowline-Figure-Eight Combo   

If you only have small trees at your disposal, it’s best to sling at least two. For top-rope anchors atop a cliff, consider this setup.  

  1. Tie a bowline knot around your first tree with static line. (Remember to back it up.) 
  2. Pull up several armfuls of slack—at least double the distance between you and the cliff’s edge. Tie a large overhand knot on a bight here. This is your safety knot. 
  3. Attach yourself to the rope between the bowline and your safety knot with either a Prusik hitch attached to your belay loop with a locking carabiner, or an assisted-braking device like a GriGri. 
  4. Adjusting your friction hitch or belay device as needed, move toward the cliff’s edge. Decide where you’d like your masterpoint and tie a figure-eight on a bight in your static line at this point. (Make sure you’re not between the masterpoint and bowline when you tie it or you’ll get stuck.) 
  5. Clip a locking carabiner to the masterpoint, lock it around the middle of your climbing rope, and toss the ends of the rope. 
  6. Slide your friction hitch or belay device along the static line to hike away from the cliff’s edge to your second tree.
  7. Use webbing or cordelette to sling your second tree. Tie a figure-eight on a bight in the ends of the cordelette and clip a locking carabiner through the loop. Affix the static line to the tree with a clove hitch to form the second leg of your anchor.
  8. Adjust the clove hitch as necessary to keep your masterpoint hanging slightly below the edge of the cliff. 

The Connecticut Tree Hitch

If you reach a belay ledge on a multi-pitch climb and find only a single strong tree available for anchoring, use your climbing rope to tie this quick hitch.

  1. Pull up a bight of slack from the belay strand. Wrap it around one side of the tree, catching the head of the bight on the other side. Pull it to the center of the trunk. 
  2. Grab the two strands of the bight’s tail end. Pull them toward the front of the trunk and push them through the head of the bight. 
  3. Clip a carabiner through the resulting hole. The spine of the carabiner should pin the tailing strands in place. 
  4. Pull more slack from the belay side of your rope. Tie a figure-eight on a bight here. This is your masterpoint. 
  5. If you’re not switching who leads, have your belayer tie a Connecticut tree hitch with their side of the rope when they reach the ledge. Only untie your original hitch when you’re safely on belay. 

Key Tips: 

  • Any tree you sling should be alive, firmly rooted, and thicker than your thick. Suspect? Give it a shake. If it wiggles at the base, move on.
  • Wrap your sling around the base of the tree to minimize the lever force on the roots. Mind your anchor to make sure the sling doesn’t inch upward over time.
  • No matter what you use to sling the tree, aim for redundancy: A loop of cordelette is automatically doubled-over, and two girth-hitched slings work, too. Only use your climbing rope if you’re really in a pinch.
  • When you pull the masterpoint toward you, the strands that depart from it to wrap around the tree should make an angle of 90 degrees or less. This helps minimize the forces on your anchor.
Photo: Dib Dab Digital

How To Sling a Boulder 

Detached blocks and boulders can protect you in a pinch. But because they’re not actually attached to the mountain, it’s best to regard them with some healthy skepticism.

The general rule is to only sling a boulder if it’s refrigerator-size or larger. Also make sure it’s on a level slope: In 2020, an experienced climber plugged a cam behind a refrigerator-sized block perched on a slope of Montana’s Granite Peak. When sudden rockfall struck the block from above, it gave way, and the climber fell 30 feet and broke his foot. The takeaway? Even big boulders can slide. When it comes to anchor building, don’t settle. 

Top Rope Setups 

If you’re setting up a top-rope anchor, it’s best practice to make the setup as redundant as possible. You can sling two boulders and equalize them as with the “bowline-figure-eight combo” tree setup mentioned above.

If you don’t have static line, you can also incorporate a boulder into an equalized gear anchor by tying a cordelette around it with a double fisherman’s knot.  

Using the Climbing Rope

If you’re multi-pitch climbing, it’s often easier to use the climbing rope itself to sling large boulders. Bonus: The rope’s thick diameter makes it less likely to get stuck in pinch points than webbing or cordelette.

  1. Make sure you’re backed up to another piece of gear, or are standing safely on a large ledge or clifftop, sufficiently far from the edge. 
  2. Pull up several armfuls of slack to make a long bight of rope. 
  3. Wrap the bight around the boulder. Pull the head of the bight back toward you. 
  4. Step a foot or two back from the boulder to leave yourself enough room to maneuver and belay. Tie the bight in an overhand knot around your strand of the rope such that you’re safely tied off to the boulder. Clip a locking carabiner through the loop made by the overhand (this is your masterpoint).  

Key Tips:

  • The block or boulder should be flush with the ground, solid, and immovable.
  • Avoid placing cams behind detached blocks of any size—the force of the cam expanding could knock the block loose.
  • Keep an eye out for sharp edges and tight pinches that could cut or trap your sling. 

How To Use Chockstones, Horns, Pinch Points, and Tunnels  

Occasionally, small rock features are big enough to support an anchor on their own, but they’re usually more suitable for one point of protection in an equalized gear anchor.  

Chockstones 

On multi-pitch routes, you may come across a rock naturally wedged in a constriction, similar to a piece of passive protection. Girth-hitches are commonly used to sling chockstones, but you can also use a doubled-over sling: Clip a carabiner clipped through the ends to create a basket hitch, or tie them together in an overhand knot on a bight and clip the loop. 

Horns 

Whenever you encounter anything resembling a protruding obelisk of rock, consider its uses. You’re looking for horn-like features that are vertical, firmly attached to the rock, and uncompromised by cracks or fractures.

If you’re setting up a belay anchor, you can simply drop a webbing loop over a horn and clip the rope to that. This works because the weight of the follower or top roper puts steady downward pressure on the sling, keeping it in place. However, if you’re leading past a slung horn, the tugging and jostling can sometimes lift an unknotted sling up over it. Consider using a girth-hitch or slip knot to gently tighten the sling around the horn.

Pinch Points

When two boulders butt up against one another, you’re left with a tight pinch point that you can occasionally loop a rope around. You can use these as anchor points provided that there’s zero gap for your sling to slip through. Also make sure the pinch is not so severe that it could trap your sling for good.

Basket hitches are effective for slinging pinch points. You can also tie a length of webbing around the pinch point using a water knot. 

Tunnels 

Certain types of rock will form hollows that look like telephone handles. They’re fun to grab and even more fun to sling, either as a piece of trad protection or as part of an anchor. Make sure the narrowest part of the arch is no thinner than your wrist and that all the rock is solid, high-quality, and free of fractures. Girth hitches and basket hitches are common when slinging tunnels.  

Key Tips:

  • Make sure chockstones are firmly wedged and won’t be knocked loose by downward or outward force. They should have flush contact with the rock on both sides of the constriction. 
  • Gently tug on any feature before slinging. If it doesn’t budge, thump harder, being careful not to knock anything loose on your belayer.  
  • Any rock feature you sling should consist of solid, high-quality rock. It should be free of fractures and firmly attached to the surrounding rock, which should be equally solid.
  • Never sling a flake or any rock feature that sounds hollow when tapped, flexes when yanked, or seems suspiciously narrow at the base.
  • Always inspect rock features for sharp edges, which could cut your sling. 
  • Never trust any rock feature or anchor point that doesn’t seem 100 percent solid.

Remember: Always inspect anchors thoroughly before weighting them. You should be well versed in belaying, lowering, rappelling, tying the appropriate knots, and cleaning anchors safely before you venture outdoors. Finally, remember that no article can fully substitute supervision or instruction from an experienced professional.

All articles are for general informational purposes.  Each individual’s needs, preferences, goals and abilities may vary.  Be sure to obtain all appropriate training, expert supervision and/or medical advice before engaging in strenuous or potentially hazardous activity.