private void setFire (Location loc, int depth)
      {
        Block block = loc.getBlock();
        Block blockDown = loc.getBlock().getRelative(BlockFace.DOWN);
        if (block.getType() != Material.AIR
            || blockDown.getType() == Material.AIR)
          {
            Block highest = loc.getWorld().getHighestBlockAt(loc);
            Block highestUp = highest.getRelative(BlockFace.UP);
            if (Math.abs(loc.getY() - highestUp.getLocation().getY()) > depth
                || highest.getType() == Material.AIR)
              return;
            highestUp.setType(Material.FIRE);
          }
        else
          {
            block.setType(Material.FIRE);
          }
      }