World Generation: New hard resources not generating correctly

[com1clyf3]

The newly added hard resources (slate, marble, etc) are not being generated through the world levels correctly. Instead of one resource every eight layers, there tend to be just two. A biome specific resource and slate.

06c9d3dd

[com1clyf3]

This is still an issue. I've loaded a world where slate goes all the way down to bedrock. And I've found obsidian at the top of mountains.

The layering seems to work in some naturally occurring cliffs, but otherwise is still broke.

5bd9f3c4

[mklingen]

This isn't broken, but working as intended. The layers go from the top down to the bottom, they don't grow from the bottom to the top. The obsidian on mountains is also intentional, in some biomes the surface layer is obsidian (namely, near volcanoes and jungles). How do you expect the layers to work?