Geology 

A geological map of Mount Vesuvius (from the David S. and Ruth L. Gottesman Hall of Planet Earth in the American Museum of Natural History)

You’ve reached the core, and
now you’re coming into granite

The great harrowing heart of it all,
where communication must cease

A new nomenclature takes shape;
it is a language without words

Under an oppressive late afternoon sun,
your faction has admitted defeat

And all the dictionaries are
being tossed into the sea