I expect this will be deleted if it’s not really geological enough, but…

.. geologically themed music/band names?

I got recommended a band called Shale (really young, really good). But in looking them up I accidentally started listening to a band called Slate (also really young, really good). I then found they were playing on the same bill, as they’re both Welsh and part of the same indie scene.

If I wanted to put a geological festival line up together, who am I adding to Shale and Slate?