Saturday, June 16, 2007

Time lapse video of migrating ripples

The previous post showed the sedimentary structure climbing ripple cross-lamination as it appears in a preserved deposit. This post links you to a fantastic video showing plan-view ripple migration in time lapse.

Unfortunately, I couldn't get this movie embedded so when you click on the screenshot at right it will take you to the USGS website where its hosted.

The movie shows a 40x60 cm area looking down on an active ripple field in a flume experiment. It is created from photographs taken once every 40 seconds for six hours. The bedforms migrate from top to bottom.

Note that these are not the highly aggradational ripple bedforms shown in the last post, but your run-of-the-mill migrating ripples.

What's interesting when watching the time lapse is how uneven the pace of the migration is. There seems to be spurts of faster-migrating ripple crests, usually in a relatively narrow strip, every so often. I don't know if the flow speed in the flume was kept doesn't say either way...but, I'm presuming it was.

Check out the index page for more movies and illustrations of bedforms in action.

No comments: