Once you think you’ve been there and done that, you find while you might have done that, you’ve never really been there. I hike to spots I’ve visited dozens of times only to experience the place as if for the first time, or in thrall to some new micro place within the whole.
In point of fact, I had never been on top of this particular rock glacier before. While some question the reality of rock glaciers, I believe those folks are mistaken. Rock glaciers are the real thing; just ask anyone who has hiked across one. There is no disputing they exist.
According to the Journal of Geophysical Research, a rock glacier is “a tongue-like or lobate body, usually of angular boulders, that resembles a small glacier, generally occurs in high mountainous terrain, usually has ridges, furrows and sometimes lobes on its surface, and has a steep front at the angle of repose.” So there you go.
There is debate over rock glaciers’ origin and mechanism of flow. The University Center in Svalbard, Norway, says, “Based on field evidence, some authors claim a general non-glacial origin for rock glaciers, while others find that certain rock glaciers contain a significant core of glacial ice.”
I remember the debate from Geology 101 in college. Some think ice underlies rock glaciers, and in places where ice glaciers proliferate, I imagine ice underlies practically everything. Rock glaciers are diverse individual features, though, and really nothing more than huge piles of rock driven by their own mass and weight to move slowly down the hill.
Around Crested Butte, where the closest we have to ice glaciers are persistent snowfields, I believe rock glaciers move of their own volition with help from nothing but gravity. Rock glaciers require a serious source of talus to create the pressure that actually pushes them into motion. Serious talus is chunks of rock that erode off the mountain above, and god knows we have plenty of that going on around here.
There are some classy rock glaciers peeling out of our mountains; so far none threatens active real estate. Rock glaciers move more slowly than ice glaciers, covering only up to a meter per year, but are still valued as efficient coarse debris transport agents. In other words, rock glaciers accomplish the job of erosion capably, helping move rock on its inexorable way down the hill. Geology in action.
Since all that rock is actually moving as one discreet mass, flow structures appear as ripples and waves. These form because everything moves all the time, just like liquid. Soil doesn’t have time to develop; rocks are continually broken and broken again by stuff falling from above. On an active rock glacier no lichen grows because it doesn’t have time to form.
From below, the nose of a rock glacier is imposing: big and steep. Rock lies at its angle of repose only by grace of its coefficient of friction. Walking up the front of a rock glacier disturbs all that and makes for rockslides; the footing is more challenging than on the grassy slope next to it.
The top of a rock glacier looks like easy walking because it appears flat. Actually, considerable topographic relief manifests as “furrows and lobes,” gullies, ravines, sinkholes, runnels and ridges. Much of that terrain lies hidden in a general mishmash of fallen and falling rock that less sensitive souls would designate a wasteland.
Naturally, we were cruising exactly that wasteland. It is the kind of place where you cross a humpy upland to confront an extremely steep-walled gully. The walls of the gully are gravel, but pummeled by rockfall to a hard and slippery surface. It is footing that led to fourteen stitches in my knee a few weeks ago, so I was particularly careful descending.
In the bottom of the gully it was quiet and peaceful with only a trickle of water under the rocks to define the dynamic nature of the place. The quiet is deceptive, like the quiet of a pinball machine just before you insert your quarter. Up-gully, the peeling face of an unnamed 13,000 ft. peak was source for rocks that during a rainstorm or spring runoff must spin through that place with random and deadly abandon.
Scrambling up the opposite wall of the gully, rocks clung only by the lightest touch of friction and slid out from under us at the slightest touch. At least there was no exposure, instead only the dead end drop back into the gully under the rockslide. On top again, we found another humpy upland and another steep gully. And another and another all hidden within a wilderness of broken rock.
As I rolled yet another ankle, I longed for green grass, alpine sod that wouldn’t shift with my weight. Still, the rock glacier was a place full of wonder, ancient snow tucked into hidden grottoes, the silence of geologic time throbbing in my ears. All that rock looked suspiciously familiar, but I was sure I had never been there before.
In point of fact, I had never been on top of this particular rock glacier before. While some question the reality of rock glaciers, I believe those folks are mistaken. Rock glaciers are the real thing; just ask anyone who has hiked across one. There is no disputing they exist.
According to the Journal of Geophysical Research, a rock glacier is “a tongue-like or lobate body, usually of angular boulders, that resembles a small glacier, generally occurs in high mountainous terrain, usually has ridges, furrows and sometimes lobes on its surface, and has a steep front at the angle of repose.” So there you go.
There is debate over rock glaciers’ origin and mechanism of flow. The University Center in Svalbard, Norway, says, “Based on field evidence, some authors claim a general non-glacial origin for rock glaciers, while others find that certain rock glaciers contain a significant core of glacial ice.”
I remember the debate from Geology 101 in college. Some think ice underlies rock glaciers, and in places where ice glaciers proliferate, I imagine ice underlies practically everything. Rock glaciers are diverse individual features, though, and really nothing more than huge piles of rock driven by their own mass and weight to move slowly down the hill.
Around Crested Butte, where the closest we have to ice glaciers are persistent snowfields, I believe rock glaciers move of their own volition with help from nothing but gravity. Rock glaciers require a serious source of talus to create the pressure that actually pushes them into motion. Serious talus is chunks of rock that erode off the mountain above, and god knows we have plenty of that going on around here.
There are some classy rock glaciers peeling out of our mountains; so far none threatens active real estate. Rock glaciers move more slowly than ice glaciers, covering only up to a meter per year, but are still valued as efficient coarse debris transport agents. In other words, rock glaciers accomplish the job of erosion capably, helping move rock on its inexorable way down the hill. Geology in action.
Since all that rock is actually moving as one discreet mass, flow structures appear as ripples and waves. These form because everything moves all the time, just like liquid. Soil doesn’t have time to develop; rocks are continually broken and broken again by stuff falling from above. On an active rock glacier no lichen grows because it doesn’t have time to form.
From below, the nose of a rock glacier is imposing: big and steep. Rock lies at its angle of repose only by grace of its coefficient of friction. Walking up the front of a rock glacier disturbs all that and makes for rockslides; the footing is more challenging than on the grassy slope next to it.
The top of a rock glacier looks like easy walking because it appears flat. Actually, considerable topographic relief manifests as “furrows and lobes,” gullies, ravines, sinkholes, runnels and ridges. Much of that terrain lies hidden in a general mishmash of fallen and falling rock that less sensitive souls would designate a wasteland.
Naturally, we were cruising exactly that wasteland. It is the kind of place where you cross a humpy upland to confront an extremely steep-walled gully. The walls of the gully are gravel, but pummeled by rockfall to a hard and slippery surface. It is footing that led to fourteen stitches in my knee a few weeks ago, so I was particularly careful descending.
In the bottom of the gully it was quiet and peaceful with only a trickle of water under the rocks to define the dynamic nature of the place. The quiet is deceptive, like the quiet of a pinball machine just before you insert your quarter. Up-gully, the peeling face of an unnamed 13,000 ft. peak was source for rocks that during a rainstorm or spring runoff must spin through that place with random and deadly abandon.
Scrambling up the opposite wall of the gully, rocks clung only by the lightest touch of friction and slid out from under us at the slightest touch. At least there was no exposure, instead only the dead end drop back into the gully under the rockslide. On top again, we found another humpy upland and another steep gully. And another and another all hidden within a wilderness of broken rock.
As I rolled yet another ankle, I longed for green grass, alpine sod that wouldn’t shift with my weight. Still, the rock glacier was a place full of wonder, ancient snow tucked into hidden grottoes, the silence of geologic time throbbing in my ears. All that rock looked suspiciously familiar, but I was sure I had never been there before.
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