Corupt block invation

Blocks are turning to dirt.

What I expected to happen was...:  ** I expected to play normally

What actually happened was...: I spawned in and blocks started to change, first it was just stone into dirt but now it is dirt just spawning in. I took some time to test the effects and it was interesting, portal blocks can turn to dirt, farmed dirt blocks popped up, and only blocks in a effected area turn to dirt. The dirt even climbed onto some blocks (look at the picture of dirt on the wood). This is crazy.

Steps to Reproduce:
1. Have a non-snapshot world
2. Exist now in snapshot
3. Big Error