Korohusk and Ram Valley (Ski, Hike, Backpack)

Ram Valley is a majestic, even magical place. It seems to float high above the Eagle River valley below. Peaks surrounding it--Raina, Pleasant, Cumulus, and Korohusk--rise higher still. Ram Valley is a vestige of another time, and is home to a glacier that never would have formed in the climate we now inhabit. Remarkably, that glacier has endured, thanks partially to a thick covering of moraine. For skiers, Ram Valley is a destination because of the steep couloirs on Korohusk.

Korohusk’s couloirs are mind-altering. Nearly two thousand feet long, they trail from the mountain top with winding, sinewy nonchalance. Not that they are relaxing: Each is 50 degrees for hundreds of vertical feet, and one couloir narrows to as few as eight or ten feet in width. It seems narrower still after sluff comes chundering down the chute and carves a V down the middle of it, making it even harder to turn down the narrow, rock-enclosed corridor. Given the steepness, it is comforting to have rocks on both sides, at least compared to the void along the narrower couloir in one area. An errant turn here would send a skier down hundreds of feet of cliffs. The narrower couloir is a remarkable formation because it is incised in a protruding, rocky ridgeline. I have never seen a formation like it, and its prominence jutting from the ridge makes the bootpack and descent even more dizzying than it would be given the chute’s steepness and constrictions.

The hazards of such lines should be obvious: Falling, particularly in firm snow, or as a result of getting knocked over by slough. The approach, of approximately seven miles, will deter more people than the challenging skiing.

Both of Korohusk’s couloirs provide a fascinating perspective on the Ram Valley glacier. From lower in the valley, it isn’t clear if the massive rock piles in the valley still hold ice, or whether the glacier is extinct. From the upper valley and from Korohusk, the ice clearly is evident in the glacier’s midsection. Ram Valley’s glacier is like many other “rock glaciers” in the Chugach and Talkeetna Mountains. For perspective on the dynamics of Ram Valley’s glacier, Louis Sass of the US Geological Survey has been kind enough to provide an expert’s perspective to my questions:

PRESS: Could you explain how the debris near the toe of the glacier insulates it?

LOUIS SASS, USGS: Debris - small amounts of debris absorbs solar radiation and increase melt rates. The classic example would be where ice appears black and wet. As soon as the debris is thick enough to be a continuous layer (which can be less than ~1 cm of fine silt) it reduces melt. Once the debris is ~ 1 m (a few ft) thick, melt rates are greatly reduced compared to that of clean ice. If you are in an area where the climate would support permafrost you can effectively have no melt whatsoever. Debris reduces melt rates, and consequently the lag time between changes in climate and changes in glacier terminus position tends to be much longer, and in many cases debris covered snouts can be left stranded by retreating glaciers. Another way of saying the same thing is that a clean ice glacier typically will retreat from the terminus, whereas debris covered glaciers often disconnect and leave stranded sections of ice down valley.

PRESS: Is Ram Valley’s glacier still moving, or ablated/dormant?

LOUIS SASS, USGS: Ram and Korohusk both show evidence of very slow ice velocities in the mid-glacier, which could be a sign that they might disconnect from thier debris covered lobes in the near future. That assessment is purely qualitative, to say anything quantitative (like number of years etc.) we would need to go out and measure ice velocites, ice thickness, and melt rates.

PRESS: In general, do rock glaciers move in the manner of other glaciers?

LOUIS SASS, USGS: Clean glaciers, debris covered glaciers, and rock glaciers are something of a continuum. We generally deem it a rock glacier once it loses any visible accumulation zone. The flow processes are the same, and are thought to only occur in bands of relatively clean ice. So a rock glacier with visible flow features has sections of clean ice internally. Those can be quite thin (maybe even just a couple meters), especially if the debris on top of the ice is thick. This is because ice deformation rates are related to the over-pressure. So very thick ice deforms under low deviatoric stresses (in plain english the deviatoric stress is basically the differential between the stress on the upstream side of an imaginary block of ice and the downstream side of that same block. It comes from the surface slope of the glacier), but likewise thin ice with a thick debris cover can also deform under low deviatoric stresses.

PRESS: What is the life expectancy of it, if you know, based on current rates of melting? How long ago were similar glaciers growing or at least stable...Little ice age?

LOUIS SASS, USGS: Rock glaciers are almost always dead or advancing, but an advancing rock glacier isn't necessarily healthy, and may in fact be totally doomed in todays climate. That goes back to paragraph 2. Ram and Korohusk are likely way out of equilibrium with climate, meaning that they recieve far less accumulation in a given year than the amount of melt that occurs. But, since the melt rates and the flow rates are relatively small, particularly at the terminus where the debris is thickest, those glaciers may not change in ways that are visible to the casual observer nearly as quickly as nearby glaciers that have less debris cover (like Organ, or Eklutna). Watching a single glacier change is kind of like watching paint dry. As a glaciologist, I look at lots of glaciers, and my eyes are drawn to glaciers that exhibit anything "interesting". Both Ram and Korohust have features suggesting the upper glacier may disconnect from the debris covered terminus "soon". But don't hold your breath...

Does it matter that Ram Valley’s glacier is disappearing? It isn’t so much that a few skiers will no longer see it, but that we no longer will get to live in its presence. From a skier’s perspective, there is nowhere else like Korohusk’s couloir slashed into a protruding ridgeline. Like all things dependent on a certain climate, that too is ephemeral.