Looks to me like 'Contour' lines on random terrain.  Here is a quick effort:

'Cap Holes', which creates the horizontal surfaces, fails in some cases.  It failed in many more until I made sure the two edges and the ends of the lofted curves were all at Z=0.  I had to sort the curve start points by X to get them to loft properly.

I'm sure there are other ways to do this...

For one thing, the lofted curves could be created parametrically instead of by hand - in fact, the surface could be created in many other ways.