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?