Loft connecting nearest points of curves

[wim (Wim Dekeyser)]

You could try the Patch command.

Note that terrain is typically modeled with meshes and you could use a Delaunay triangulation - see this thread for more info on that:

Pointset Reconstruction - PLUGIN

It is still available, but no longer developed or supported. The plugin contains known crash bugs. For better implementations of Delaunay and Voronoi (both 2D and 3D), you can use Grasshopper. http://en.wiki.mcneel.com/content/upload/files/PointSetReconstructionTools.zip