Unit 03 · Weathering, Erosion & Soil
This unit follows rock as it comes apart and moves: physical weathering that breaks rock without changing it and chemical weathering that rots it from the inside, erosion that carries the pieces away, deposition that lays them down, and the soil horizons that build slowly where all of this comes to rest. Mastery means you can read a landscape as a balance of weathering, transport, and deposition — a surface always being remade, not a fixed backdrop.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Physical & chemical weathering | Cannot tell physical weathering from chemical, or thinks rock does not really change. | Names both kinds but cannot give an agent or example for each. | Distinguishes physical from chemical weathering, names the agent driving each, and predicts which dominates in a given climate. |
| Erosion, transport & deposition | Thinks landscapes are fixed and erosion is negligible. | Names the agents (water, wind, ice) but cannot link energy to what gets carried or dropped. | Relates the energy of a moving agent to the size of sediment it carries and explains where and why deposition occurs. |
| Soil formation & horizons | Treats soil as inert dirt with no structure. | Names the horizons but cannot say how they form. | Reads a soil profile top to bottom and explains how weathering, climate, and time build each horizon. |
| Landforms as evidence | Sees landforms as permanent and unrelated to any process. | Links a landform to an agent in general but not to a rate or timescale. | Reads a valley, delta, or dune as the signature of a specific process working over deep time. |
| Lab technique (stream table) | Runs water over the tray without controlling slope or flow. | Observes erosion but cannot connect it to a variable. | Controls slope and flow in a stream table and connects the erosion and deposition pattern to the variable changed. |
| 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. |
“The fast water in the steep part of the stream table cut a channel and carried the sand, then dropped it in a fan where the slope flattened and the water slowed. Hutton looked at unconformities like that and realized the Earth had to be almost unimaginably old — ‘no vestige of a beginning.’”
“The hills have always looked like that. Erosion is too slow to matter. Soil is just dirt.”
You demonstrate this unit through stream-table erosion and deposition runs plus short oral checks where you reason from the evidence aloud — not a multiple-choice test. A criterion counts as mastered only when you can both produce the pattern at the tray and justify the process behind it. 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.