[X] My Assistant

[ngunn]

Mars discussion is a bit thin at the moment due to the conjunction but I could not let this pass without thanking Emily for yet another superb article elucidating a highly complex topic.

http://www.planetary.org/blogs/emily-lakda...hypothesis.html

The idea that the last liquid water on an increasingly airless Mars would have worked its geological magic under a covering of snow makes a lot of sense.

[mcaplinger]

The idea that the last liquid water on an increasingly airless Mars would have worked its geological magic under a covering of snow makes a lot of sense.

The paper is well worth reading, but as it says in section 6.2, it really doesn't address the valley networks and alluvial fans. (It tries, but doesn't completely succeed to my taste.)

As a general rule, explaining Earthlike morphology with non-Earthlike processes needs a high level of motivation. ("If it looks like a duck", etc.)
IMHO, section 1 oversells that motivation in the case of early Mars, though I need to read Haberle 1998, which I hadn't recalled was so definitive. But as a jumping-off point for discussion, the paper is very good.

[ngunn]

As a general rule, explaining Earthlike morphology with non-Earthlike processes needs a high level of motivation.

True, but Mars morphology is not always Earthlike. One reason I like their idea is that it provides a way to build structures like the Gale crater mound by making windblown sediment stick preferentially in particular places favourable for snow melt. From a purely terrestrial perspective Aeolis Mons is more like a surrealist painting than a geological construct.

[mcaplinger]

True, but Mars morphology is not always Earthlike... From a purely terrestrial perspective Aeolis Mons is more like a surrealist painting than a geological construct.

I'm not convinced that a lot of geomorphologists would agree with this statement. If the mound is an erosional remnant instead of being formed in place, I'm not sure it's that remarkable on its own.