On a March visit to the North Carolina seashore, I encountered this tableau (above) of two types of markings on an otherwise pristine sand dune. One of them seems to be a trail left in the surface by a passing arthropod. The other has a mound-like relief and it appears to have been made by the sand being pushed upwards from below. The mounds鈥� height and width are generally uniform along their length, at perhaps 1 and 1.5 centimetres, respectively; there are branches at several points; and nowhere do there seem to be openings to the surface. Does anyone have an explanation?
Howard Ritter, Fuquay-Varina, North Carolina, US
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