Really Funny And Strange CHUCNK ERROR

Put the summary of the bug you're having here
Well, i was logging into a new minecraft world to see if my HEXXIT had installed properly. i didnt click flat land so when i spawned on what looked like a flatland i was confused. i fly up and noticed that this was not flat.
this was a MASSIVE chunk of dirt and stone and the sort of shiz in the middle of the snow biome. i know this isnt a bug. its just my first chunk erro and i was rather a shock to see this. the first picture is looking up.