if (!_generating_world && Chance16(1, 10)) {
                bool chance = Chance16(1, 16);
                /* Note: Do not replace "^ SLOPE_ELEVATED" with ComplementSlope(). The slope might be steep. */
                res = DoCommand(tile, chance ? cur_slope : cur_slope ^ SLOPE_ELEVATED, !chance,
                        DC_EXEC | DC_AUTO | DC_NO_WATER, CMD_TERRAFORM_LAND);
            }