Sliced Off Land

I don't know if this is supposed to be a normal thing now or not...but it seems kind of strange.
I installed the new server and MC version with no problem, but when I started looking around on my map, I found these areas here and there in a new set of chunks that almost look like some one took a knife and sliced open a cross section of land. They are completely flat faces of rock under dirt, with ocean right next to them.

Also, I have yet to be able to locate a single mesa over several different maps.