I tried to resist posting this so soon... but I just couldn't make myself NOT share it! I think this might be the "best" picture I've ever gotten. My comments are in pink - it's only slightly less harsh on the poor students' eyes than red.
I told them they could illustrate exam answers, but only if a) their illustration was clearly labeled and b) their picture was literally worth 1000 words.
This one might be worth 1000 words, but I'm willing to bet that the words would not be strung together in any sort of logical, meaningful sentences...
For those non-geologists who are thinking there's some way to make this work, this link is more or less what the student was supposed to be getting at...