You can add hills to your terrain with a single mouse click. You can control the height of a hill as well as its peak shape. Generally, the diameter of the hill base is the same as the hill height. You can insert multiple hills together to create one larger hill. Also, if you insert hills next to other terrain elements, like plateaus or slopes, the elements will automatically blend together.
To insert a hill or valley:
Select Insert
> Terrain > Hills/Valleys, or click the Hills/Valleys
button on the Terrain toolbar.
In the Hills/Valleys dialog, specify the height of the hill in the Height edit box. Entering a negative value will create a valley.
Using the Zenith slider control, select a peak shape for the hill.
Click OK.
Click to insert the hill. You can insert multiple hills if you like.
Right-click and select Finish.