A little help?

hi all, i nee some help, im making a flash banner for the website to our exhibition in my class for end of year.
weve been given a theme to stick to, firen and ice, dont ask.
anyways, weve decided on everything, we know what it will look like.

we have a logo, all i need is a volcanic rock looking thing.
its something like 800 by 200 but its ok i can crop if need be.
all i need is an image of dark brown rock, with molten cracks that show the bright lava in it, but i need it up close, and taking up the lower half of the banner dimension, it will be the foreground, looking out at sky, with fire coming out of it, and smoke, and snow flakes falling down with our logo in the midst of it, ive dont the snowflakes *and rather well i must say)
weve got the fire, weve got the logo, weve got everything, but an image of vlcanic rock looking stuff, and im no good at photoshop and we want it sort of realistic looking, if someone can make one or even find one, although ive tried looking through google :stuck_out_tongue:
it would be very much appreciated. unfortunately no moolah involved.
but yes, a rather long image of it would be better with different types of cracks, that way ill just choose which bit to use then…
if noone understands, then tell me and ill sketch the sort of thing i want fr you, just dont have much time now, sorry if ive confused you.