Skip to comments.Transverse instability of megaripples
Posted on 03/20/2012 8:12:20 PM PDT by smokingfrog
Two kinds of sand ripples exist: normal, small ripples and megaripples with wavelengths reaching up to several meters. They differ also in their grain-size distributions (unimodal for sand ripples and bimodal for megaripples).
While sand ripples form almost straight lines, megaripples have greater sinuosity due to their transverse instability, a property that causes small megaripple undulations to grow with time.
The origin of the instability is due to variations in megaripple height, which do not diminish over time, as well as to the inverse dependence of ripple drift velocity on height. Thus, the taller regions of ripples will move more slowly than the adjacent, shorter portions, an outcome that promotes further perturbation growth.
(Excerpt) Read more at physorg.com ...
Where is that, SF?
Indeed. But can it be used to eliminate the washboard in my gravel roads?!
Please define the definition of the various variables.
I’m interested in that I live within easy driving distance of some of the largest dunes aka ripples in North america
Argentine Puna Plateau
Tranvestites and megaripples? Hmmm!
Dunes are not simply larger ripples (although they are sometimes called "megaripples"), even though they share the same basic morphology as ripples. In general, dunes form by the migration of sediment up the stoss slope and down the lee slope, forming cross beds that are homologous to cross laminations. Eddies on the lee side form a distinctly scoured trough.
Dunes range in height from 5 cm to over 10 m and form in fine to very coarse sand and gravel. Straight crested dunes produce planar cross beds. Sinuous and lenticular dunes produce trough cross beds.
OK, so, this is bad, but I first read this as: Transvestites insist on meganipples.
It’s not just me, right?
Simply blading over washboard and filling the depressions
between the ridges is nearly useless. The best method is to
cut all of the material loose to a depth of 1 inch or more below the bottom of the washboard area. This brings up some fines to mix with the surface material. Then transfer the material to the proper crown and shape.
But remember that one cause of washboarding is dry conditions. ‘Never work on washboarding problems without good moisture in the material. When possible work the problem areas after a good rain and then resume normal blading.
I don’t get what this thread is about, something about waterboarding transvestites with meganipples?
Well, that’s whatever you were talking about for you.
... and I'll drink to that, too!
Thanks. It was not familiar to me.
I thought I could get some actual geologists to jump in on this thread, but I guess not...
I’m not “actual”, only “associated” with.
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