Friday Field Foto #55: Antidunes!
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.