Make two terrains using the PHY MAKE command with a file name, say
ScapeA for the first and ScapeB for the second
Use a third variable, say Land that can be set to either terrain.
The PHY LOAD command is pretty fast, so once you have both terrains
built and saved, you're good to go.
Notice that both terrains are loaded at the same time, but only
the currently visible one will be active.
EDIT: I've included a simple example. To see the second terrain,
click the mouse. You can move the cube with the arrowkeys. Actually,
the terrain in this example is huge, 18 miles on a side.
Terrain switch:
phy delete rigid body ScapeA
hide object ScapeA
phy load rigid body static terrain ScapeB,"LandB.scp"
show object ScapeB
Land=ScapeB
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