ESP_034801_1300_1.0xA piece of Mars: On the floor of a crater in the southern midlatitudes, there’s a field of ripples. But wait, there are big ones that are very sinuous and small ones that are not. Why? Both are ripples, but they’re different kinds of ripples. The smaller ones (~3 m, or ~10 ft) are probably made entirely of sand, while the larger ones (~15 m, or 50 ft) are older and they’re probably made of a mixture of different grain sizes. (ESP_034801_1300, NASA/JPL/Univ. of Arizona).

Comments (3)

  1. Woaaaaaah cooooooooooool.

  2. That is a rather complicated image. Why are the larger ones not anchored where the bedrock pops up (the yellow)? They almost look fluvial (in the broad use of the term). But they are very sharp for that. Between them from the ripples you can see the wind has been deflected. Very interesting image.

    1. Hi Chris! I’d imagine they aren’t anchored because there’s too much sediment relative to the size of the terrain roughness (boulders in this case, it looks like). They look sharp partly because of the sun angle — this is the southern midlatitudes and it’s winter, so the sun is low in the sky. They might also look sharp if they’re active, so this is a good place to request further imaging. Nobody’s ever seen the larger ripples on Mars move.

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