Muir Snowfield: is it a glacier?

I think the definition of "movement" concerning glaciers can also include melting of ice (compression) and sheering of ice layers. Most of the glaciers in the lower 48 United States are "pocket" glaciers, (think of the Sierras glaciers). I think that the Muir has more than enough evidence to prove that it moves, and is large enough to be called a glacier. On the other hand, the Palmer "glacier" on Hood, is more of a marketing ploy for the majority of laymen skiers/snowboarders. I think that the Palmer would have been long gone by now without the intervention of Timberline. (Packing, salting, strawing) They are now pulling snow from White Salmon glacier with Forest Service approval.....(and I thought throwing tons of salt was pushing it!)

I think that many marginal Cascade glaciers like the Muir snowfield are remnants of much larger features. In their more active days they moved a good deal and created moraines that is evidence of that movement. They became crevassed. Now, however, these icefields are downwasting so much that for many there is little, if any, movement. The crevasses that are seen always tend to be in the same places and reappear not from movement, but from ablation which removes overlying snowcover and bridges, re-exposing old and stagnant crevasses. Observations indicate to me that most 7000' locations on glaciers have lost 100-150' of ice over the past 30 years.

The crevasses that are seen always tend to be in the same places and reappear not from movement, but from ablation which removes overlying snowcover and bridges, re-exposing old and stagnant crevasses. Observations indicate to me that most 7000' locations on glaciers have lost 100-150' of ice over the past 30 years.

<br><br>It's interesting to think that the MS's stagnant crevasses may be decades, hundreds...thousands of years old? I bet they've collected a lot of junk in them over the years.<br><br>So you're saying that at 7000' most glaciers have lost 100-150' vertical depth of ice? Any guesses on how deep the snowfield may be at it's deepest spot?<br>

Jibber

So you're saying that at 7000' most glaciers have lost 100-150' vertical depth of ice? Any guesses on how deep the snowfield may be at it's deepest spot?

<br><br>I really have no idea on the age of these Muir icefields. Although last week near Rainy Pass at 7000' I found a recently deglaciated area (still with a small patch of receding ice) and among the detritus there was an old, rotten, fallen larch. Now the odd thing was that this larch was some 500' higher than any existing tree in the area and, in fact, only a few young larches not older than 20 years were growing at similar elevations nearby, and none within several hundred yards of this relict larch. Yet the relict larch was quite large. So my belief is that larch fell or was overrun by an advancing glacier during the early stages of the Little Ice ages and has only recently been exposed. That would mean the larch fell some 600 years ago and that this area has not been ice free since then (or it's remnants would be long gone.<br><br>Some glaciers readily show their thickness if you kind of imagine the terrain, but the Muir snowfield, being convex doesn't give any such indication. So, I have no idea of it's thickness. But, yes, glacier down-wasting seems to have amounted to some 100-150' since the 1978 timeframe. Of course, on some glaciers, especially bigger and more active ones, there aren't really any markers that give one an accurate guage of thickness change except near moraines. So that is why I limited my observations to glaciers near 7000'. The moraines are usually readily visible and they aren't so thick that it is difficult to approximate their downwasting.

This thread reminded me of an interesting Master's thesis I stumbled upon discussing variation in Rainier's glaciers by Thomas Nylen in 2001 www.glaciers.pdx.edu/Nylen/Nylen_Thesis.pdf Pages 39 & 48 have some possibly relevant numbers that could help us guess at the Muir snowfield thickness...<br><br>The USGS 1994 data records that the Muir snowfield had an area of 0.98+/-0.02 sq.km. and an 'estimated volume' of 0.02+/-0.01 cubic km. This works out to an average depth of around 20 meters... at least 10 years ago and with some sizeable error bars. Also note that these numbers were similar to 1971 data so Muir could be more stable in the last 30 years than other receding glaciers.<br><br>I'd imagine that depth variation across the snowfield might be in the 10 to 30 meter range. Enough to get my attention if a sizeable crack opens up. For comparison, a table on page 71 shows the thickness for some of the major glaciers on Rainier such as the Emmons (94 meters), Winthrop (70m), Carbon (181m!), Tahoma (77m) and Nisqualy (81m).<br><br>

Thanks Straka!<br><br>Great information, and nice to hear from you.<br><br>So are you in for a Lodge Lake 2006 soaker fest? I understand that ronj will be on the lookout for a cold and rainy day for us again this year