Earth Systems, Plates & Earth Materials — Extension · Science 6: Matter, Energy & Earth Systems, Grade 6
How can properties and indirect evidence reconstruct Earth’s processes? What formation histories are supported by a supplied rock packet, and where must identification remain uncertain?
Use evidence to explain Earth materials
Investigate
What formation histories are supported by a supplied rock packet, and where must identification remain uncertain?
Three 35–45-minute sessions: plan and predict; examine or collect evidence; explain, revise, and reflect. Use the complete supplied record when materials, time, access, or safe conditions are unavailable.
Materials
- Four supplied specimen/process cards and an evidence table.
- Paper for a labeled rock-cycle pathway and a plate-motion sketch.
- Optional known parent-selected safe specimens for observation only.
Before you begin
Use cards or intact known specimens. No acids, sharp scratch tests, breaking rock, powdered samples, excavation, or travel to hazardous slopes is required.
Plan an evidence comparison
The packet compares formation evidence, texture, and stated process history. Keep observations separate from supplied process information and inferred classification. A missing history must remain unknown, not be invented.
Method
- List each card’s observed feature and any separately supplied process record. Mark which statement is observation and which supports an inference.
- Apply the definitions of igneous, sedimentary, and metamorphic formation to the packet. Explain the process rather than use color alone.
- Keep card D provisional and name what additional evidence could distinguish possibilities.
- Draw at least two branching rock-cycle pathways linking the classified materials, with weathering, erosion, deposition, cooling, or metamorphism labeled accurately.
- Use the supplied plate-marker distances to calculate mean relative motion, then explain what that short record cannot predict.
- Write a 150–200-word evidence explanation connecting Earth materials and processes. Revise a forced one-route cycle and record one uncertainty.
Supplied illustrative record — use when an actual test is unavailable
Illustrative classroom data authored for analysis, not measurements from a real learner, stream, product, or field study. Actual observations may differ; record them honestly and compare the methods.
| Card | Observed feature | Supplied process record |
|---|---|---|
| A | Interlocking crystals | Molten material cooled and solidified |
| B | Fragments cemented in layers | Sediment accumulated and was cemented |
| C | Mineral alignment in solid material | Heat/pressure changed the rock without complete melting |
| D | Dark, fine-grained appearance | No formation record supplied |
| Plate markers | Separation 200 cm, then 208 cm | Matched measurements four years apart |
Analyze and explain
- Classify A–C from their stated formation evidence. What remains uncertain for D?
- Why can weathering and erosion not be used as identical labels?
- Show one alternate rock pathway, with no forced order through every category.
- Calculate the relative plate separation rate and distinguish it from a future-earthquake prediction.
What a strong explanation includes
- Formation categories linked with their process evidence.
- Unknown history retained for D.
- At least two accurate branching pathways.
- Correct 2 cm/year relative rate and a limit.
- A meaningful model revision with explained reasoning.
Parent / teacher guide: discuss after the investigation
A is igneous in the supplied formation record because molten material cooled and solidified. B is sedimentary because sediment accumulated and became cemented. C is metamorphic because solid material changed through heat and pressure without complete melting. The textures support those explanations, but the definitions depend on process; dark color by itself does not make D uniquely igneous. D needs more evidence, such as mineral and texture observations or a trustworthy formation context. A branching cycle can show A weathering into fragments, erosion carrying them, deposition accumulating sediment, and cementation producing a B-type material. A could alternatively change through metamorphism or later melt. C could also weather rather than be forced through an igneous stage. Weathering changes material in place while erosion transports it, so their arrows should not be interchanged. The marker separation increases by 8 cm over four years, giving a mean relative rate of 2 cm/year. This describes the stated interval between those markers. It does not give each individual plate’s speed, require identical future motion everywhere, or predict an earthquake date. The combined report should identify an observation, explain a supported process, retain D’s uncertainty, and show how a model was revised rather than hide incomplete evidence behind a confident label.
Compare this model with the learner’s actual evidence. Different measurements can support a different conclusion; check the reasoning and limitations, not matching wording.
Extend the chapter investigation by evaluating its evidence and proposing a better test.
Problem 1
Answer and explanation
A is igneous in the supplied formation record because molten material cooled and solidified. B is sedimentary because sediment accumulated and became cemented. C is metamorphic because solid material changed through heat and pressure without complete melting. The textures support those explanations, but the definitions depend on process; dark color by itself does not make D uniquely igneous. D needs more evidence, such as mineral and texture observations or a trustworthy formation context. A branching cycle can show A weathering into fragments, erosion carrying them, deposition accumulating sediment, and cementation producing a B-type material. A could alternatively change through metamorphism or later melt. C could also weather rather than be forced through an igneous stage. Weathering changes material in place while erosion transports it, so their arrows should not be interchanged. The marker separation increases by 8 cm over four years, giving a mean relative rate of 2 cm/year. This describes the stated interval between those markers. It does not give each individual plate’s speed, require identical future motion everywhere, or predict an earthquake date. The combined report should identify an observation, explain a supported process, retain D’s uncertainty, and show how a model was revised rather than hide incomplete evidence behind a confident label.
Problem 2
Answer and explanation
A is igneous in the supplied formation record because molten material cooled and solidified. B is sedimentary because sediment accumulated and became cemented. C is metamorphic because solid material changed through heat and pressure without complete melting. The textures support those explanations, but the definitions depend on process; dark color by itself does not make D uniquely igneous. D needs more evidence, such as mineral and texture observations or a trustworthy formation context. A branching cycle can show A weathering into fragments, erosion carrying them, deposition accumulating sediment, and cementation producing a B-type material. A could alternatively change through metamorphism or later melt. C could also weather rather than be forced through an igneous stage. Weathering changes material in place while erosion transports it, so their arrows should not be interchanged. The marker separation increases by 8 cm over four years, giving a mean relative rate of 2 cm/year. This describes the stated interval between those markers. It does not give each individual plate’s speed, require identical future motion everywhere, or predict an earthquake date. The combined report should identify an observation, explain a supported process, retain D’s uncertainty, and show how a model was revised rather than hide incomplete evidence behind a confident label.
Problem 3
Answer and explanation
A is igneous in the supplied formation record because molten material cooled and solidified. B is sedimentary because sediment accumulated and became cemented. C is metamorphic because solid material changed through heat and pressure without complete melting. The textures support those explanations, but the definitions depend on process; dark color by itself does not make D uniquely igneous. D needs more evidence, such as mineral and texture observations or a trustworthy formation context. A branching cycle can show A weathering into fragments, erosion carrying them, deposition accumulating sediment, and cementation producing a B-type material. A could alternatively change through metamorphism or later melt. C could also weather rather than be forced through an igneous stage. Weathering changes material in place while erosion transports it, so their arrows should not be interchanged. The marker separation increases by 8 cm over four years, giving a mean relative rate of 2 cm/year. This describes the stated interval between those markers. It does not give each individual plate’s speed, require identical future motion everywhere, or predict an earthquake date. The combined report should identify an observation, explain a supported process, retain D’s uncertainty, and show how a model was revised rather than hide incomplete evidence behind a confident label.
Problem 4
Answer and explanation
A is igneous in the supplied formation record because molten material cooled and solidified. B is sedimentary because sediment accumulated and became cemented. C is metamorphic because solid material changed through heat and pressure without complete melting. The textures support those explanations, but the definitions depend on process; dark color by itself does not make D uniquely igneous. D needs more evidence, such as mineral and texture observations or a trustworthy formation context. A branching cycle can show A weathering into fragments, erosion carrying them, deposition accumulating sediment, and cementation producing a B-type material. A could alternatively change through metamorphism or later melt. C could also weather rather than be forced through an igneous stage. Weathering changes material in place while erosion transports it, so their arrows should not be interchanged. The marker separation increases by 8 cm over four years, giving a mean relative rate of 2 cm/year. This describes the stated interval between those markers. It does not give each individual plate’s speed, require identical future motion everywhere, or predict an earthquake date. The combined report should identify an observation, explain a supported process, retain D’s uncertainty, and show how a model was revised rather than hide incomplete evidence behind a confident label.