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Friday Field Foto #55: Antidunes!

June 13, 2008

Man, this week has been crazy … just one of those weeks, I guess … I haven’t had a chance to sit down and catch up on any of the happenins in the geoblogosphere. I apologize to anyone I’ve left hangin’ in any discussions going on.

Instead of links and useful information (that stuff takes more time than you think!) … for this week’s Friday Field Foto, I’m simply going to post a photo and a bonus video of some antidunes. Everybody loves antidunes! My post about the submarine cyclic steps briefly discussed supercritical flow, which is what produces antidunes. One of the best places to find antidunes is where a stream comes out at a sandy beach. In the photo below, the current is going from left to right. In supercritical flow, the bedforms are “in phase” with the fluid wave and migrate upstream (from right to left).

The photo is okay … but the video is key (even if the resolution of the video function from my digital camera is craptastic). Watch how the standing waves grow and migrate (slowly) upstream (away from the camera) and then break. If the video isn’t embedded properly, go here.

Happy Friday!


3 Comments leave one →
  1. June 13, 2008 6:46 pm

    Having lived a few steps from the beach half my life and realizing just now that the small ‘mud mounds’ that form when sea water retreats in the shore are actual antidunes, I can’t say anything else than ‘ohhh righhttt’ followed by ‘cool!’.

    Thanks Brian, nice post.

  2. June 13, 2008 8:30 pm

    Miguel … once you start watching antidunes, you can’t stop! They’re mesmerizing.


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