A plateau is a relatively large, flat area of land situated above the adjacent land. Adding a plateau to your terrain involves clicking a few points to define the shape of the plateau. You can control the height of the plateau as well as its peak shape. Note that if you insert a plateau in close proximity to other terrain elements, such as hills, the elements automatically blend together.
To create a plateau:
Select Insert
> Terrain > Plateaus, or click the Plateaus button on the
Terrain toolbar.
In the Plateaus dialog, specify the height of the plateau in the Height edit box. Entering a negative value creates an excavated area.
Using the Zenith slider control, select a general shape for the plateau. The pointier the shape, the steeper the sides will be.
Click OK.
In the drawing area, select points to define the outline of the top of the plateau. Note that the last point picked always closes back to the start point, so you don’t have to pick the start point again. The plateau will be created downward and outward from your outline.
Right-click and select Finish.