The Thin Ice Handbook: Understanding The Ice

This is part 2 of 3. Stay tuned tomorrow for Part 3: Techniques for Climbing Thin Ice.

How many times have you started up an ice climb in thin conditions and found it to be drastically different than you anticipated? The difference between perceived and actual conditions can be subtle or startling. The key is not to ignore that feedback, and to incorporate it in your decision-making in the moment, and for the future.

Usually ice climbs—especially thin ones—are harder than they look from below. Being surprised on lead is something most people try to avoid, but calibrating one’s eye to accurately judge the reality of a climb takes experience and, for most of us, a few—or many—terrifying retreats. What if you could improve your accuracy when estimating conditions?

Reading ice as a climber will always be an imperfect science. The interplay of objective and subjective factors is part of the intrigue—and if we’re paying attention, the education, too. Dry, wet, delaminated, fractured, plastic, cauliflowers, ‘chandeliered,” colorful, gray, melting, fat, thin, fragile or bullet proof … ice is a hyper-variable medium. If we can bring constancy in our approach with good information, mechanics, fitness and equipment, we can meet the variability with the precision of a practiced eye and skill set. Here are a few thoughts to improve your literacy in the frozen medium.

[Heathy, bonded, well formed ice: ideal for reliable placements.]

The good, the bad and the ugly
Pure ice is really strong stuff. It can be clear if it doesn’t contain many air bubbles, or soil particles. Snow that falls while the ice is forming—and sun, just about anytime—introduces air that will make ice more opaque, even when it’s thin. This can make it difficult to gauge thickness. Ice in different areas may show a variety of colors, tones of blue, green and yellow are the most common. This can indicate a strength and vitally or freshness in newly formed ice—or simply be a reflection from minerals, other particles that reflect that color of the visible spectrum.

[Thin “cauliflower” formations offer little protection and limited security considering their volume.]

When ice has more air in it, it’s weaker. Also, as the air content goes up, ice may appear more white or gray. Especially in thin ice, these blanched tones often indicate more brittle, fragile or older formation. Some air in the mix can be good for easier tool placements, because the ice is less dense. Neve is an example of the threshold where tools and crampons place easily, but the medium isn’t reliable/ dense enough for ice screws.

“Snice” is a snow/ice mixture one step beyond neve toward snow, where tools and crampons may not support bodyweight. The take away: Density is important. If climbs form while it’s snowing, you can get some very strange and very weak surface features and lenses that are fragile or deceiving— they may look more substantial than they are. Bleached, “foamy” looking ice is often the result of too much sun. Key off these indicators and try not to be fooled when a climb looks, “good from afar but is, in fact, far from good.”

[Cold temps, dry conditions, and brittle ice that formed in a flash freeze would require a lot of cleaning and a measured approach.]

When the going gets thin
Broadly defined, thin ice conditions fall on a spectrum, from not being able to place a reliable ice screw where you’d want, to a virtually useless volume of ice, even for the pick of a tool or front point. Generally, less than five or six inches of good, bonded ice can feel limiting. And utility often decreases from there. The steeper a climb is, the more the thickness of the ice you’re climbing seems to matter. Conceptually, for me, thin ice means climbing where there’s less room for error and a greater requirement for precision.

Going beyond the surface
New ice is usually more textured. Older ice is often smooth or scalloped. Weather morphs the surface ice through wind, snow and temperature swings. The ice that’s close to the exposed surface goes through numerous changes with these fluctuations. If temperatures have recently dropped, the surface ice will be more brittle while the ice beneath the surface stays a more consistent temp and is more accepting of a pick. Temperature patterns that are even, or gradually warming—but still below freezing—are usually ideal climbing conditions for thin routes.

Strong in compression, but weaker in shear
This has to do with technique, but it’s relevant to the discussion of ice as a medium. When relying on a tool placement, maintain a downward pull in line with the shaft of the tool and stay under your tools—gripping the low pommel is usually preferable. This is especially important with a “hook” type of tool placements. In this construct, you are compressing the ice under your pick. Foot placements are similar: set the points and maintain even, downward pressure, keeping your foot level. Pressing into the ice on steep moves is beneficial; however, lateral pressure, to the left or right on contact points increases the likelihood they’ll shear out.

Consider water flow and what conditions created the climb
When did the ice form? Is it still growing, fully formed or deteriorating? Is it the result of ground water, a rain event, snow melt through the season or a seep? Did it build over a season? Or is it the result of a flash freeze event? Each answer can give you clues about what to expect around the quality and reliability of the ice on the climb. 

[Anne Gilbert Chase finds the best placements swinging in the ice-choked crack. Delaminated ice on the periphery of the flow is easily fractured and less reliable.]

Notice how the ice is bonded to the rock
This bond dictates a lot of what you can get away with in terms of placement security and protection. Early season, water flow, air temperatures, sun exposure, recent snow and rock temperature are a few significant variables that may affect how good, (dense/aerated, strong/weak, reliable/unreliable) the ice and its bond to the rock really is.

If it’s just too thin, poorly bonded, or unprotectable
Notice “dry” options near by. Climb high enough on those weaknesses—cracks, edges or corners—to enter the climb higher on thicker ice. This scenario can lend its self to climbing thin ice with the added security of rock protection.

[Erik Eisele listening (and feeling the vibrations) on the toe of this south facing line, Hackett Tremblay—dark rock, thin ice and solar exposure are an unfortunate combination. Overcast, below freezing days, at a time when the climb is still building, constitutes the essential element of timing for a route like this.]

Listen when you’re swinging and kicking
It may seem obvious, but the sound that is created by these actions can tell you a lot about whether the ice is bonded to the wall behind it. For climbs that receive sun, this is particularly important. Other “loud,” sketchy climbing may be the result of a recent thaw or of climbing on the margin of a high-volume flow. Early in the season, when the ground and rock are still just either side of the freezing mark, this is a hazard, and it’s worse when topping out. Generally, vibration and hollow sounds are cause for greater concern and distrust.

Knowledge of ice as a medium is difficult to communicate well due to its many variables. Reading ice conditions effectively takes a lot of field time and observation connecting cause and effects consistently. If nothing else, I hope these thoughts get readers asking some good questions in developing their own eye for conditions and making foundational decisions around what they find when they investigate ice as a medium.