decaying layers???

anyone know how to make a layer look like it is decaying (you know with big chunks falling off and stuff) or know where there is a tutorial for this?

i know about the brush strokes --> splatter method, but i'm looking for something alot more dramatic.

thanks alot.

i think i figured it out, but thanks to anyone pondering an answer, and for those who are curious to what the hell i was talking about, this is what i figured out.