Sometimes gravel will end up in trees.

I just finished making a world with the seed " -4032470951044633259 " and at the coorinates " X: -245, Y: 85, Z: 301, F: 56.28775 " Here there are two blocks of gravel sitting on a tree, and the cause unknown. Thanks for the time.

To recreate this glitch follow these steps:
1. Create new world using Minecraft 1.7.2, use the AMPLIFIED world type. Creative mode.
2. Use the seed -4032470951044633259 for the world with the glitch.
3. Teleport to these coordinates exactly: X: -245, Y: 85, Z: 301, F: 56.28775 .
Notice the gravel on the trees.