Random Terrain & Hit Test

programming
1

Here’s the sitiation. I’m making a pocket tanks-esque game, but I’ll be using cannons and you cannot move. Here’s the deal:

2 Questions:
1st) Using 1x1 pixels how can I generate random terrains with a top 1x1 pixel black border?
2nd) How can I make these 1x1 pixels disappear when the cannonball explodes in a certain area? (i.e. Pseudo code)

 
onhit.Test(cannonball && ground)
   playmovie(explosion) at cannonball._x && cannonball._y
   remove.this.cannonball.MovieClip
If hit.Test == True
  Remove movie clip(ground) where
  explosion == ground._x && ground._y

I realize my coding is really bad and not in syntax, but I was just trying to get the gist of it across as I was writing it down in my notebook earlier.

If I’m not able to make a random terrain, it would still be appreciated if I could make a terrain that was always the same, but using those small 1x1 pixel mc’s, but I don’t know how I’d do that. Would I just use a duplicate for, command to populate a boxed in area? And how do I define the boxed in area?

Thanks for the help in advance