Unit 04 · Metamorphic Rocks & the Rock Cycle
Metamorphic rock is stone remade in the solid state — reshaped by heat and pressure deep in the crust without ever melting. This unit covers foliated rocks and the slate–phyllite–schist–gneiss sequence of rising grade, non-foliated rocks like marble and quartzite, the reasoning that recovers a rock's protolith, and the full rock cycle that ties igneous, sedimentary, and metamorphic rock into one continuous system — Hutton's Earth, endlessly recycled with no vestige of a beginning. Mastery means you can name a metamorphic rock, infer what it used to be, and trace a single mineral grain all the way around the cycle.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Heat & pressure without melting | Thinks metamorphism means the rock melted. | Names heat and pressure but not that the rock stayed solid. | Explains how heat and pressure recrystallize a rock in the solid state, short of melting. |
| Foliated vs non-foliated | Cannot tell banded from unbanded rock. | Labels foliation but cannot say what causes it. | Distinguishes foliated from non-foliated rock and explains foliation as mineral alignment under directed pressure. |
| Metamorphic grade (slate → gneiss) | Treats all foliated rock as the same. | Orders part of the sequence but misplaces phyllite or schist. | Orders slate, phyllite, schist, and gneiss by rising grade and reads increasing heat and pressure. |
| Protolith reasoning | Cannot say what a metamorphic rock started as. | Guesses a protolith without evidence. | Infers the protolith — limestone to marble, sandstone to quartzite, shale to slate — from texture and composition. |
| The rock cycle (lab) | Treats the three rock families as unrelated. | Names the rock cycle but cannot route a grain through it. | Traces a mineral grain around the full rock cycle, linking igneous, sedimentary, and metamorphic paths. |
| Integration (cross-domain) | Treats the science as isolated facts; makes no cross-domain connection. | Names a link to history, reading, or writing but cannot defend why it matters. | Connects the unit to its anchor across History · Reading · Writing (plus chosen electives) and defends why the connection matters. |
“This is gneiss — it has coarse, banded light and dark minerals, so it was squeezed and heated to a high grade without melting. Its protolith could have been granite, or a shale that went slate, phyllite, schist, then gneiss. Melt it and it re-enters the cycle as igneous rock.”
“It’s a striped rock that got hot. I think it melted a little. I don’t know what it was before.”
You demonstrate this unit at the specimen bench — identifying metamorphic rocks with a hand lens, inferring each one's protolith, and sorting rocks by their place in the full rock cycle aloud — not a multiple-choice test. A criterion counts as mastered only when you can both name the rock and defend the protolith and cycle path it records. Mastery is demonstrated, not awarded.
A 5-page clipboard packet — unit overview, key terms, the mastery rubric, anchor examples, and a score sheet you can print and grade against.