Pathological Geomorphology

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    Parabolic [not Barchan] dunes / marauding jellyfish advancing north of Winnemucca

    3-20-2010_8-28-26_am

    One of my favorite geo-vignettes in Nevada is the sheer weirdness of a troop of barchan dunes advancing through a small rural community north of Winnemucca. These dunes are remnants of deposits from Lake Lahontan back in the day when it was huge and now they heading 'back East'.

    Check out the image in GE or FE and trace the course of the dunes (or marauding band of jellyfish?) from their source to their ultimate sink on the Humboldt River floodplain.

    Dunes in a trailer park? Gotta see it...

    Tags » aeolian desert
    • 20 March 2010
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    about 2 years ago Kyle House responded:
    Kyle House
    Callan discreetly pointed out to me that, if these dunes are barchans, then they must be travelling to the west. Actually, these dunes have a very strongly eastward migration vector. You can actually check it out it google street view and see that the slip-faces are on the east sides of the dunes where they cross the highway. Also, the predominant wind in northern Nevada is, by far, from west to east. You can also check the context of the image and discern that the dunes are moving from a sand-rich area (dried up Pleistocene lake bed) to a sand-poor area.

    I have always considered the two types of arc-shaped dunes (crescentic and parabolic) as different manifestations of the 'barchanoid' shape, one with leading arms (crescentic) and one with trailing arms (parabolic). It seems that some sources distinguish parabolic from barchan / crescentic, however. I will consult my better resources at the office next week, get some better data, and post some examples.

    Thanks to Callan for brining up the question!

    about 2 years ago Kyle House responded:
    Kyle House
    According to my old DRI colleague, Nick Lancaster, these dunes are parabolic dunes. Sorry for the misinformation and thanks to Callan for calling me out. To paraphrase Nick's book*: parabolic dunes are U shaped with trailing vegetated arms and unvegetated noses or dune fronts that advance by avalanching.

    Sorry for the early misinformation.

    *Lancaster, N, 1995, Geomorphology of Desert Dunes. Routledge, London. 290 p.

    9 months ago Josiah Gardiner liked this post.
    9 months ago Howard Isaacs liked this post.

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