Carvers do not cut through any other blocks than default overworld blocks.

If you put some other block than stone, diorite, granite, andesite and possibly other blocks in that generation, (For example Blackstone) old carvers will be cut off when they hit that block. Noise caves generate through that block normally.

Steps to reproduce:

1. Download the Blackstone Caves
2. Import it to a new world
3. Generate the world
4. Look at the carvers.
5.  → They start at the dirt, but stop at the blackstone.