04/14/2021
How to Assess Sandstone After Rain or Snow
Categories: Access and Conservation , Tips
From the soaring splitters of Indian Creek to the immaculate desert varnish of Red Rock, sandstone makes up some of the most incredible climbing in the world. Unfortunately, it is also some of the most fragile. While the Nuttall sandstone at the New River Gorge is actually harder than granite, most sandstone is weakened to an incredible degree by moisture. As a porous rock type that can absorb a lot of water, western sandstone from Utah to California can lose up to 75% of its strength while wet, making it easy to snap off holds and irreparably damage classic climbs. The bottom line for climbers: Don’t climb on wet sandstone, full stop.
But this is sometimes easier said than done. While staying off the stone for 24 to 48 hours after it rains is a no-brainer, many factors such as aspect, wind, season, and amount of precipitation have an impact on how long it will take sandstone to truly dry off and be safe to climb again. When climbing on sandstone, consider the following factors.
How much precipitation fell?
While a brief, passing storm may largely run off the rock and allow climbing within a day, it could take days after a heavy downpour or snowstorm for sandstone to truly dry out.
How humid is it?
Drier conditions will lead to faster evaporation. Humid weather, conversely, will extend the drying-out period.
What is the crag’s aspect?
South or west facing crags that get lots of sunlight will dry out faster than north and east facing crags that are shaded most of the day. Similarly, cloudy or overcast weather will extend drying times.
Is it windy?
Brisk winds can accelerate the drying process.
Is there evidence of moisture?
Even if the surface of the rock is dry, it is entirely possible that moisture is lingering in the subsurface. Is there damp ground on the approach? Is there any wetness at the base of the rock? If you dig down an inch or two into the dirt at the base of the crag, is there underlying moisture? If the answer is ‘yes’ to any of these questions, there is probably still moisture under the surface of the rock.
Take all of the above factors into account after precipitation on sandstone. If it’s a bright sunny day after a light rainfall, with dry conditions, the rock may only need 24 to 48 hours to be climbable. If it’s humid and cool following a downpour, you may need to wait several days or even a week. It is never worth rushing: The route will be there … as long as the holds don’t break.