Got the vertical cave in my village

Got the vertical cave in my village

One day, I changed the Java version form 1.8.0 64bit to 1.8.0_b20 64bit,
and I got the vertical cave in my village.

And I changed the Minecraft version form 1.7.10 to 1.8-pre2, the cave has exists.

In Minecraft version 1.7.10, I can jump to the cave.
In Minecraft version 1.8-pre2, I lost my lift used Shift+W key near the cave.

Attachment is form Minecraft version 1.8-pre2.