yes this is a very broken world. maybe the seed? or optifine? idk. wanna know what an open ravine would look like? sure. this is NOT a build, it has been created by the world or seed itself or something. again, idk.
So just playing Minecraft on optifine and found a cave hole so thought, why not go down it? Turns out, I nearly die and find this infinite cave or ravine of some sort. It may be the texture pack was faulty, a strange seed or optifine broke. I'm not sure but there's a picture I've added so check it out for yourself.