Chunk error

A chunk error is a common error found most often in multiplayer mode. It can sometimes be seen in singleplayer, but seems to be less common. Chunk errors are startling, but are often times harmless. They are only client side, meaning that other users cannot see the chunk error unless under some very rare circumstances. To fix them you usually just need to re-connect to the server or reload the map. You cannot jump or fall into a chunk error but it has been reported that you sometimes might fall into a chunk error and fall into the The Void. There are also numerous reports of mobs glitching from The Void all the way to surface rapidly back and forth. Note that items dropped on a chunk error WILL fall and cannot be retrieved. Also, non-solid blocks can't flow into one.

Other times you may find a chunk error in which you find part of a mountain. The mountain is generally cut right down one or more sides. This is useful for finding caves and precious minerals.

Usage of chunk errors
When you experience a chunk error, you will most likely see valuable minerals and dungeons. If you have a buddy on a multiplayer server with a chunk error, they are useful for guiding a friend along the sides of a chunk error as they can see where you are digging. This means that your friends can point them to resources your friend cannot reach because of the chunk error.