[The Saucepan Man]

OMG Now Esty has an alter ego!!!

Er - snow angels ...

Legolas watched them for a while with a smile on his lips, and then he turned to the others. "The strongest must seek a way, say you? But I say: let a ploughman plough, but choose an otter for swimmming, and for running light over grass and leaf and snow - an Elf.

With that he sprang forth nimbly, and then Frodo noticed as if for the first time, though he had long known it, that the Elf had no boots, but wore only light shoes, as he always did, and his feet made little imprint in the snow. (Emphasis added)

That tells us four things:

1. This is an ability of Elves generally, not just Legolas.
2. It involves running lightly.
3. It involves being nimble.
4. His feet did make some imprint in the snow, but not much.

I draw from this that Elves, being lithe and nimble, were able to redistribute their weight so that they ran lightly, reducing the weight placed on the surface and leaving only a light impact. My guess is that this would require a conscious effort, since there might be occasions when they would wish to step more heavily.

Laying in the snow, an Elf would have nowhere to redistribute the weight of his body to, and so I would conclude that an Elf's snow angel would be as deep and marked as a man's.

I believe that this issue (Legolas' light step) is addressed in the book on the Science of Middle-earth that I noted a while back. Lalwendë, you have the book don't you? Does it shed any light on this question?