The last post talked about walking on rocks in general terms. My own assessment is that there are a lot of specifics that have to be considered with every step one takes. They all figure into when you take the next step, where, and how. If you really want to break it down there are at least eight separate attributes of the rocks in front of you that you are constantly assessing before each next step. Whether you do this consciously or unconsciously depends on where you are in your journey.
Each rock has:
Elevation - higher, lower, or even with last step?
Size – smaller, equal to, or larger than your foot?
Shape – flat, round, jagged, pointed, knife edge?
Attitude – flat, sloped forward, back, left, right? Degree of slope?
Texture / Friction – smooth, rough, wet, dry, covered in snow, ice, hail, lichen?Spacing – small, medium, or large next step, a jump away, a leap away?
Stability – solid or resting balanced and subject to shifting when weighted?
Route finding – does it lead to a next step?
Elaborating on each of these attributes is instructional.
Elevation
When the next step is at the same elevation as the last one, and you are neither climbing nor descending, it’s a simple step. When the next step is higher, you have step up and place your weight further forward, maintaining upward momentum to avoid falling backwards. When the next step is lower, you have to control the rate of your descent to assure your leg can bear the additional weight caused by downward acceleration, and you have to keep your weight centered or back slightly to avoid falling forward. When wearing a 25-50 pound pack, evaluation the elevation of the next step is even more important. When you’re over 50, wearing a 50 pound pack, and have badly worn knees like old duffers I can think of, you should be evaluating why you are there at all!
Size
Is the rock – or more precisely the surface of the rock onto which you will step – big enough for your entire foot? If it is, then the simple step is to allow your entire foot to contact and weight the rock. If it is not, then you want to place your foot precisely on that part of the rock that gives your foot the most support, closest to the center of the sole of your boot, which is directly under the center of your leg. Misplacing your boot off center will create torsion stress on your ankle and lower leg muscles and could cause loss of balance. Of course in the Beartooths it is not uncommon to encounter very larger boulders – say the size of cars and trucks – as well. Finding a place for your foot isn’t the challenge!
Shape
Large, flat, level, rocks linked one to the next without gaps are often referred to as a sidewalk. There is a resting point on the col along the East Ridge route up Granite Peak that we called the sidewalk, but that was a bit of a stretch. It was level however and big enough for a half dozen people to sit and rest so it was definitely a sidewalk by comparison! But rocks are rarely flat and level. Depending on where you are in the Beartooths the rocks can be predominately rounded shapes or they can be fractured rocks that present jagged or knife edges, or points. Stepping to a rounded rock that is bigger than your foot is the simple step. Stepping to a pointed rock smaller than your foot or a knife edged rock, even if it is three times longer than your foot takes concentration. It also depends whether the knife edge is running along or across the long axis of your foot, or somewhere in between. The desired step is to put the point or knife edge in the center of your boot to minimize ankle and lower leg stress and to maintain balance. While walking at 10,947 feet on the top of Beartooth Pass, Alex has all sorts of choices… knife edge, point, knife edge, or point? “Now let’s see, my next step is….?”
Attitude
Like the “attitude” of an aircraft, the surface of the rock onto which you step can be straight and level or it can be pitched up so the surface of the rock faces you, pitched down so it slopes away from you, or rolled (sloping) to the left or right. If the rock surface is long and narrow it can also be aligned with your direction of travel or yawed some number of degrees (like a compass needle) to the left or right of north. Also like an aircraft, the surface of the rock you are about to step on can deviate from center in all three of these planes at once! When about to step on a rock that is tilted away, sloping steeply to one side and rotated more than 15 degrees, it’s not uncommon for some of us to take a quick inventory related to the integrity of our ankle and knee ligaments and the support provided by our boots.
And while you’re processing all of that you have to avoid being distracted by the beauty of the rock under your foot!
Texture and Coefficient of Friction
Texture and coefficient of friction, are pretty closely related because one contributes to the other. Sometimes it is easiest to grasp a concept by first considering the extremes. Consider trying to stand on an ultra smooth freshly Zamboni’d ice rink in hard leather soled dress shoes. Now consider standing in high-top thick soled boots, surfaced with really soft rubber, on a board through which very sharp nails have been driven one half inch apart for several square feet. In the first example it would be nearly impossible to stay standing unless one was an accomplished circus performer. In the second, nearly anyone could stay standing even if the bed of nails was sharply tilted. These examples speak to a concept in physics known as coefficient of friction. I’m not suggesting that anyone hiking in the mountains spends their time doing mental calculations for the coefficient of friction for each rock they are about to engage, but it is safe to say that they are assessing the likelihood that their foot will stay on the rock when they place it and weight it there. For the most part granite rocks in the Beartooths have a high coefficient of friction. That is, if you’re wearing good boots with soft rubber soles, your foot will stick to a rock even if the surface you step on is angled 45 degrees or more. But if you’re stepping on a rock that is wet from rain, or in a stream and covered with moss, or even if it is dry but heavily covered in loose flakey lichen, then the coefficient of friction will be small and the likelihood of slipping off the rock is high. Descending a thirty degree slope consisting of Volkswagen sized boulders covered in two inches of hail (think ball bearings) was a very low coefficient of friction experience Pete Shelley and I shared while hustling off the 12,047 foot summit of Sky Pilot Mountain in a lightening and hail storm last July. The camera didn’t come out for that particular experience, but here’s another photo that leaves one thinking about coefficient of friction.
Spacing
Everyone has their own comfortable step spacing when walking. Of course we all started out with baby steps that grew larger as we did. They reach some maximum length as we mature and then reverse the trend and shorten again as we age. At any given age, depending on leg length and hip, knee and ankle flexibility, we each have our own most comfortable and efficient stride. When walking on rock you often have to take steps that are shorter or longer than your natural stride to land on what you’ve determined to be the next most reliable rock. In the decision making sequence when evaluating where to put your next footstep, stride length is a lower priority than a number of the other attributes described here. For example it doesn’t matter how perfect the rock fits your gait if it’s tilted at an impossible, ankle breaking angle, or if it is moss covered in the middle of a stream. Shorter than natural steps are usually easier than longer than natural steps, though often less efficient. On a twelve mile hike where you might be taking more than thirty thousand steps while gaining six thousand feet, maximizing your efficiency seems highly desirable. Of course if you’re young, and efficiency isn’t part of your calculations, it is easiest to just FLY over the rocks!
Continue to follow if you are inquisitive - and have the time. Don’t if neither exists.
Regards,
JR
