Linguoid ripples in snow?
Georgia Perimeter College professor Pamela Gore sent me these photos yesterday of some interesting structures she found in the snow in her yard. She was away for the storm itself, so she didn't watch them forming, but the morphology suggested linguoid ripple marks to her. If that's accurate, the current direction (wind direction) was from the north. Take a look at her photos below, and here's some photos for comparison.
Two shots that are zoomed and cropped from the image above:
Pamela e-mailed me again this afternoon to say that, "Looking at them in daylight, they look like they were formed by impacts of snow [clumps] from trees, landing at an angle and causing folding on the 'downstream' side."
What do you think? Are these linguoid ripples? Any sedimentologists want to chime in?
Two shots that are zoomed and cropped from the image above:
Pamela e-mailed me again this afternoon to say that, "Looking at them in daylight, they look like they were formed by impacts of snow [clumps] from trees, landing at an angle and causing folding on the 'downstream' side."
What do you think? Are these linguoid ripples? Any sedimentologists want to chime in?
Labels: georgia, primary structures, snow
4 Comments:
Callan, has there been any melting of the snow? The times I have seen snow ripples form are in nice snow fields. Course, that is mostly what we have around here ;-) My impression is that it usually needs to be cold enough for the snow to act as separate grains rather than wet where they clump/adhere to get true erosion & migration bedforms. This field/lawn has a lot of vegetation exposed making me think some melting has occurred. I have seen similar features resulting from partial melting and also from re-exposure of older impressions (footprints?). Anyone else have any ideas?
Hi Mel!
I don't know about melting -- given that this is in Georgia, I wouldn't be surprised. I'll leave it to Pamela to answer that question.
I'm dubious of the ripple hypothesis for the reason you mentioned: it has to be really cold for the snowflakes to act as coherent grains that don't stick to one another.
Plus -- these features seem to thin and too steep to be proper ripples. I'm reminded more of pahoehoe "ropiness" in the skin atop a lava flow.
I'm going with Pamela's e-mailed explanation of this morning -- that there was some folding of an upper flexible layer of snow due to cratering.
C
it's from melting snow above dripping onto the ground snow... i have it in my yard too-under a huge tree!
Having spent my whole life in the Great White North, my first instinct was: impact craters from snow-pats falling off a tree. That snow looks too wet and goopy to drift under any wind conditions. Then I scrolled down and saw that Ms. Gore has nailed it, IMHO.
--Howard
Calgary, AB, Canada
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