waffle what version is that O.o
i have 1.1.2 but yours has "_01" at the end. was there update?
also my clouds arent cubes they are planes(flat as paper D:)
oh and yea DEFINITELY dig into teh heart of a mountain. i found 3 huge cave systems. 1 had like 5 pits of lava and i got diamond and gold and redstone it is an awesome mine
however i keep hearing skeletons and spiders but im nowhere near the surface. could this mean dungeon? cause if so imah stay away from the skeletons, they deal soo much damage on hard xD. also i heard that the cave music means theres a dungeon.