A chunk that was loaded since May(Minecraft 1.8.1) was replaced in 15w47c in another chunk, 100 blocks further. This happened with 3 chunks.
However, the water from the river biome, was saved on the place of the cave (second picture)
Environment
Windows Vista: 32-bit, 4GB RAM
Java 8 Update 65 32-bit
Linked issues
duplicates 1
Comments 2
Sounds like MC-74762 then.
Currupted world, did you have a world, which had the exact name, deleted just before creating this one?