This blog entry is a total cheat.
I'm simply referring you to a couple of pages on the internet to be awed by some chalk drawings that will blow your mind. (with a nod to The Divine Though Blogless Elizabeth who shared them via email). It's truly worth the two minutes to look at this you tube slide show.
Those are nice, moderately tame things (well, except perhaps for the shark). But this guy ... makes sidewalks almost scary! But damn are they awesome!
Here's a video of how Edgar Mueller (and team) made the Cravasse in Dun Laoghaire for the "Festival of World Culture" which took place from August 21. to 24, 2008.