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Roadside snow stratigraphy at Lake Tahoe
Interesting roadside snow stratigraphy (I thought that should be
"stratiography" but Webster's says "stratigraphy") at Lake Tahoe at the end of this winter. If you drive along roads where big snow-blowing snow plows, instead of pushing snow back onto the banks at the sides of the road, have cut away the snow deposits on the shoulders, leaving vertical walls of snow, you see similar striking stratigraphy all around the Lake. You get an edge view of many very distinct tree-ring-like horizontal layers of snow, typically an inch or so thick, such as might arise from some rippled or toothed edging on the snow removal machinery, but I think do not. I've not stopped to examine or count these layers carefully, but starting at the ground level there may be a dozen or more such layers, which I suspect trace back to a series of daily storms in late December. It seems reasonable to assume that differences in daytime and nighttime temperatures will give a primarily daily character to these layers. Then there's a single very distinct, quite thin, dirty black layer, which I assume comes when the snowfall stops for a period of multiple days and dirt thrown up by passing cars and maybe falling pine needles pile up on the snow surface. Then on top of this another 12" to 18" of daily strata, representing probably the January storms that passed through the area; then another black layer; and another series of thin layers from February. Above this, nearing the top of the existing snow, things tend to get messy, because the top layers have been melting, or even gotten rained on a little, and the top edge of the vertical bank has curled over. Every once in a while there will be a roadside structure of some sort -- a low stone wall, a raised culvert, even just a roadside bush -- and one can see all of these layers "hump up" and curve continuously over that point. I suppose all of the above is something that observant people see every winter, in lots of other places at well, and I've just not noticed before. However, the phenomenon seems to be particularly distinctive this winter, which may be due to (a) the series of distinctive and prolonged storms we had here this winter, and (b) perhaps increased use of snow-blowing machinery, as contrasted to older snow plows that just push snow off the road into big banks on the shoulders. Anyone have pointers to more formal studies of these stratigraphic records? |
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#2
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Roadside snow stratigraphy at Lake Tahoe
In article ,
AES wrote: Anyone have pointers to more formal studies of these stratigraphic records? The evolution of the snowpack over the season is the basis of all avalanche hazard estimation. The "standard" reference book there is "The Avalanche Handbook". In terms of other fields, most of that kind of analysis of the snowpack happens in the Antarctic. There was an PBS show a few years back of a climb of a new route on Mt. Vinson in the antarctic w/Jon Krackuar where digging snow pits and examining the layers was part of the expedition. _ Booker C. Bense |
#3
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Roadside snow stratigraphy at Lake Tahoe
In article ,
Booker Bense wrote: In article , AES wrote: Anyone have pointers to more formal studies of these stratigraphic records? Ask in sci.geo.geology and sci.geo.hydrology. The evolution of the snowpack over the season is the basis of all avalanche hazard estimation. The "standard" reference book there is "The Avalanche Handbook". In terms of other fields, most of that kind of analysis of the snowpack happens in the Antarctic. There was an PBS show a few years back of a climb of a new route on Mt. Vinson in the antarctic w/Jon Krackuar where digging snow pits and examining the layers was part of the expedition. UNR has Tahoe records which should go back the late 1890s when they started using the Rose Snow Sampler. There's a national repository of ice cores near Boulder. It depends what one wants to do with stratigraphy. Most people think chemistry, but others do physics. Still others do other things. CA DWR holds lots of stuff. The old project I worked on is still around. -- |
#4
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Roadside snow stratigraphy at Lake Tahoe
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