Areas looks like swiss cheese

I get lots of deep holes in every biome in every world I tried.

What I expected to happen was...:
Nice curvy hills/biomes

What actually happened was...:
lots of large/deep holes that destroy the overall feeling, might be nice for expeditions but even they don't want this many in the same small area. Building a town or village would require a lot of patching holes.

Steps to Reproduce:
-

 

Can'ät select Pre-release 2 for some reason.