Calculated Risk & Climbing: Stone

“I stand up next to a mountain. And I chop it down with the edge of my hand.” — Jimi Hendrix
Breaking stone with the edge of my hand. Image Source

Stone has been built up as the great invincible mountain to be conquered. It is why we climb, & it is what we climb, but, as climbers, we oft forget that is also something that must be treated tenderly.

While there is an entire field of study dedicated to the innumerable types of rock, their hardness, composition, & so on; climbers usually care about a single characteristic.

Will it hold me?

The answer is always, “It depends.” Assessing your stone before you climb on it should always be a priority. How to assess the stone can be broken down into three categories: Porous, Attachment, & Weather.

Porous Rock

Porous is the most fascinating type of stone, being able to absorb & disperse liquids relatively quickly. It includes rock types like sand- & limestone. Porous rock presents a variety of hazards, & is perceptibly more probable to break when wet. Wet sandstone is weaker. Spring or Fall freeze/thaw cycles create fractures of all sizes (micro- through macro-). Chemicals or minerals in rainwater can react with limestone to literally wash away the stone.

Midwestern Sandstone. Source: Wikimedia Commons

Note that all rock is susceptible to this type of wear, but I break out porous rock as is needs particular inquisition. This author once was bounced down eight feet of ledges after a hold broke on a warm up problem. Sandstone: the outside was dry, but the inside was still wet. It had rained 2 days prior.


Weather & weathered. Storied above, wet rock is more susceptible to breakage. Snow melt, temperature changes, freeze/thaw cycles, wind, & all types of aberrant weather affect stone. Take note of weather in your climbing area up to a week before you climb. If there has been precipitation of any kind within the last 3 days, it is safer for you & the rock to not climb. *Note: this is an average, not an absolute, weather from more than 3 days past can affect your climb.

Weathering comes in many forms outside of natural events. Humans primarily. Be aware of the impact on popular climbs. The most chalked holds are also the most weary holds. Remember that the common apologia, “Everyone else was doing it.” Will not stop gravity. Give holds a good whack before setting all your weight on it. Sage wisdom from Kevin, “Climb lighter.”

You’ve seen holds polished from hundreds of climbers, think what occurs to roof jugs, crux gastóns, even the worst of slopers, after hundreds of slaps, grabs, & cliffhanger tributes.


Unlike your crazy ex, you want it to be attached. Check how and why a rock or hold is attached to the rest of the wall. Watch out for root growth, ice, dirt, debris or anything else that appears to be between the hold & the rest of the rock. If it’s not attached, it’s not a hold.

Big Rock Fall. GIF Source

Flakes. Knock first. If it sounds hollow, the safety buffalo says don’t climb on it. Cams & flakes: even if the flake appears to be solid, the outward force generated by falling on a cam can be multiple times the force of the fall.

What can I do with this knowledge?

Climbing is about making informed decisions to manage the risks you are taking by calculating whether they increase the risk to you, your partner’s, or other’s safety.

Rock failure is one of the top reasons climbers get injured, or worse. Being able to do a basic assessment of the stone you are about to climb is paramount to being able to climb safely. Rock that is wet, worn, cracked, or unattached provides a clear indicator for a safety concern.

Wear a helmet while you are climbing, while you are belaying, & even when you’re just hanging out around a crag. You cannot predict every rock fall, and one can only prevent the most obvious of instances.

When bouldering, make sure that you are being actively spotted, and that others are outside of your fall zone. Warm up problems can be most problematic, especially with experienced climbers: one’s skill level is but a single of many, many factors that can result in a fall.

Further reading: Flakes, Jugs, and Splitters: A Rock Climber’s Guide to Geology. By: Sarah Garlick.

Climb safe, climb more, & climb happy!

A Note On Conservation

On top of the safety concerns for the climber, belayer or spotter, & those nearby, climbing on rock that is wet, weathered, or otherwise flakey has the potential to change a route for future climbers. The Regular Northwest Face of Half Dome was forever changed last in July 2015, when a 5 million ton flake simply fell off the face.

This might be an extreme example, but think of your favorite route or problem: what would happen to it when the crux crimp or mainstay roof rest disappears one day? Will others be able to climb that same route? If this happens to enough climbs, will the area have to be closed?

Choose conserve your climbing areas.

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