I logged onto my world like normal right? then when i spawn into my world it just goes crazy with glitches.My world is superflat and I fly over towards some of my buildings and one huge wall just appears out of nowhere.It's a wall of stone with all of minecraft's ores and stones.i see oceans and lava like in a normal world right?.It's just a huge wall that cuts off straight down.I have taken screenshots of this as well.These wall are all around the edge of my world.you can fly over them and see an original minecraft world with oceans and trees.There were also trees along with grass and flowers within 3 blocks of this strange wall.I'm very concerned with what has happened in my game.