“Life is 90% Attitude.”

but it sounds pretty…solid to me.

I see what you did there. I, for one, think it’s a rock solid pun that most will take for granite.

That layer will also include, worldwide, levels of radioisotopes that do not occur naturally. The same way that there is an Iridium layer on the soils of 65MYA showing the asteroids that killed the dinosaurs, the current sediments being laid down have traces of plutonium and other materials that will exist until the sun becomes a red giant and swallow the Earth.