Raise/lower terrain effects on rockiness

[Yitzi]

When you raise or lower land, it can affect rockiness, as follows:

-If you raise a flat square to an elevation of 1000m or more, it has a 25% chance to become rolling.
-If you raise a rolling square to an elevation of 2000m or more, it has a 20% chance to become rocky.
-If you lower a rocky square to an elevation of under 2000m, it has a 2/3 chance to become rolling.
-If you lower a rolling square to an elevation of under 1000m (but still land), it has a 50% chance to become flat.