I feel through a glitch in the world and can't get out.

When I walk around, I often see glitches - where you can see through the ground to what's underneath. That's no big deal - as you get closer to the area, it resolves and you just see the normal stuff.

This time, though, it didn't resolve and I fell into the black empty area. I can sort've navigate as I fall and end up in a mineshaft I created, but after a few minutes, it throws me back into the empty blackness and I go back to falling. I can't seem to get out of this glitch.

I can ZIP up the Save folder for you to look at, but it's 14 MB - larger than the 10 MB attachment limit.