I thought this was an interesting phenomenon. Wave-induced sand ripples, that were merging into a tide pool at the base of the cliffs at Rhossili on the Gower Peninsula, had curvilinear and compressed dendritic drainage channels in the narrow valleys between the ridges.
Inch Strand is a wide beach on a sand spit that reaches out like a peninsula into the sea at right angles to the mainland on the South Coast of the Dingle Peninsula in Ireland. We walked the entire five kilometres of dune-backed shore as the tide was receding. By the time we turned back from the tip of the spit, the ebbing sea had left behind acres and acres of wonderful patterns in the sand, in sculptural forms the like of which I have never seen before. I was totally captivated by these designs, looking as did like elaborate knitting or crochet stitching. Here are just a couple of examples of the patterns in the sand.
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