Rock Glaciers in the Cascades?

[Jake]

Are there any rock glaciers in the Cascades besides the one on Star Peak? What is the one on Star like? I neglected to visit it when I was there several years ago - can you tell there is ice under all the rock?

[catbirdseat]

I was there and I couldn't really tell. It was October and there was no snow anywhere. It looked just like smal talus and scree. The rocks all moved very easily underfoot. We were never sure about exactly what a rock glacier was.

 

I was able to find this definition:

"Rock glaciers like this one, in the San Juan Mountains of Colorado, are rarer than ice glaciers. A rock glacier takes a combination of cold climate, a copious supply of rock debris, and just enough of a slope. Like ordinary glaciers, there is a large amount of ice present that allows the glacier to flow slowly downhill, but in a rock glacier the ice is hidden. Sometimes an ordinary glacier is simply covered by rockslides. But in many other rock glaciers, water enters a pile of rocks and freezes underground—that is, it forms permafrost between the rocks, and ice builds up until it mobilizes the rock mass.

 

Rock glaciers may move very slowly, only a meter or so per year. There is some disagreement over their significance: while some workers consider rock glaciers a kind of dying stage of ice glaciers, others hold that the two types are not necessarily related. Certainly there's more than one way to create them. For more photos of rock glaciers and a taste of current research, visit this page at Queen's University of Belfast. " Link

Edited February 18, 2005 by catbirdseat

[klenke]

I'm not sure where the rock glacier is on Star Peak but there are a couple of candidate locations (brown dotted areas on the map).

This photo hints at what it would look like (bottom-right):

 

There is also a rock glacier below the macroscian North Face of Mt. Bigelow nearby to Star Peak. It doesn't look like much but you can tell where it is (the forested prow cleaves it):

 

There are some others in the Pasayten I believe, but I can't recall off-hand where they are. I could be mistaken, though.

[Alex]

Give the South Cascades Glacier a few more years.

[klenke]

Except, of course, that a regular glacier can't become a rock glacier at some future date from recession or whatever. A rock glacier forms in its own special way (see CBS's post above).

[COL._Von_Spanker]

Sounds like we got ourselves a couple of armchair climbers turned armchair glacial geomorphologists...

[ncascademtns]

There are some others in the Pasayten I believe, but I can't recall off-hand where they are. I could be mistaken, though.

 

Ptarmigan Peak has a nice rolling rock glacier on south side. I called it Physiological Peak because you could never see the summit until you actually got there from the base.

[klenke]

This is the south side of Ptarmigan Peak:

There is no rock glacier there and I would find it highly unusual to find a rock glacier on a south-facing slope--especially in the Pasayten where glacier ice is hard to come by. The south slope is rolly polly tundra-like land (heather and rock and dirt, etc..). However, there may well be a rock glacier on the north side. I don't remember reading of one being there.

 

Here's the largest glacier in the central Pasayten (east side of Mt. Lago). Not much, is it? And this was taken in 1998. No telling what shell of this is left now:

Or maybe the one below Lago's North Face:

[PONCHO&LEFTY]

There may be one on or near Silverstar

[MisterMo]

I had once thought and been led to believe that the roly poly rock pile you cross between Stuart Pass and Goat Pass, as when approaching Stuart N side from Ingalls Lake, was considered a rock glacier. The original brown Beckey guide refers to it as such, I think.

[klenke]

MisterMo: Indeed. I was unaware of this one on Stuart.

It is in the old brown Beckey and is mentioned in a variation for the W. Ridge (p. 307):

"Variation: North Side of Lower Ridge:

From north side of Stuart Pass or from lower west ridge before its N.W. face traverse and climb scree N.W., then into the large gully at the head of the rock glacier."

 

It must be the talusy slope with the snow aprons in this photo:

[Jake]

Ptarmigan Peak has a nice rolling rock glacier on south side. I called it Physiological Peak because you could never see the summit until you actually got there from the base.

 

I remember there to be lot of rock on Ptarmigan - and a nice case of dehydration as well...

 

This is all interesting though. What other curious geological features are out there in them thar mountains?

[MisterMo]

What other curious geological features are out there in them thar mountains?

 

Boulder Pass has some really standout roof pendants. I doubt these are any form of a rarity at all but the ones at Boulder really leap out at you.

[Jake]

What are roof pendants?

[MisterMo]

What are roof pendants?

At the risk of totally butchering geologic concepts and terms: Roof pendants are chunks of overlying country rock above and protruding down into a (once) molten plutonic mass.

[Dru]

Except, of course, that a regular glacier can't become a rock glacier at some future date from recession or whatever. A rock glacier forms in its own special way (see CBS's post above).

eh...if you read cbs post with proper level of reading comprehension you will see a regular glacier CAN become a rock glacier.

[marylou]

There is one somewhere by Oval Peak in the Twisp Rv area. Discussion on this, and links to more rock glacier stuff can be seen here.

 

I was in that general area a couple of times last summer and wish I'd known to go have a look.

 

 

[jordop]

Not in the Cascades, but this was a very cool one I saw last summer off the Duffey Lk Rd in BC: