SCIENCE · INVESTIGATE AND EXPLAIN

Separate burial pressure, temperature and differential stress

Metamorphism changes mineral assemblages and textures predominantly in the solid state. Parent composition, temperature, pressure, fluids and reaction time determine which transformations are possible. A limestone can recrystallize toward marble, while quartz-rich sandstone can form quartzite; neither must become foliated merely because it experienced heat.

Learning outcome: Compare two gradients at the same depth, then two depths at the same gradient. Retain unit conversions and distinguish a pressure calculation from a stress-fabric claim. Propose a mineral or contact observation that could constrain the path independently.

Starting recap

Separate observation, material inventory, process model and historical inference. State units and the evidence that could reject a proposed explanation.

All lessons are open directly. Your saved experiments remain when you leave and return.

Try

At 15 km and 25 °C/km, pressure is 397.305 MPa and temperature 390 °C. A 35 °C/km path at the same depth has the same load pressure but temperature 540 °C.

Open the experiment

Predict

Can equal-depth rocks differ in temperature without differing in load pressure?

Your prediction and reason

Experiment

Compare two gradients at the same depth, then two depths at the same gradient. Retain unit conversions and distinguish a pressure calculation from a stress-fabric claim. Propose a mineral or contact observation that could constrain the path independently.

Separate pressure and temperature along a supplied burial path

Worked teaching model · synthetic values · Uniform overburden density2700 kg/m³, g9.81 m/s², surface15°C. Lithostatic pressureρgz, temperature15+gradient×depth. A simple path, not a calibrated geotherm, differential stress, melting boundary or prediction of an actual metamorphic assemblage.

Burial depth: 15 km Linear geothermal gradient: 25 °C/km

Reset keeps your prediction, captures and practice history.

Two rocks at the same pressure can experience different temperatures and mineral reactions.

Lithostatic pressure is not directional differential stress. Parent composition, fluids, reaction time and stress affect assemblages and fabrics. Metamorphism is predominantly solid-state change; crossing an actual solidus would require a separate melting model.

Complete quantities under the stated assumptions
Quantity	Value	Unit
Depth	15	km
Lithostatic pressure	397.3050	MPa
Temperature	390	°C
Temperature increase above surface	375	°C

Retain the prediction and settings before comparing explanations. Replayed supplied observations are not new specimens, independent field samples or practical certification.

Two rocks at the same pressure can experience different temperatures and mineral reactions.

Observation to attach to a capture

Captures preserve recipes and replay their calculated results. They are synthetic model evidence, not physical measurements.

Understand

1. Define the geological question

2. Build the mechanism and evidence ledger

Differential stress can align platy minerals or promote fabric development. Slate, phyllite, schist and gneiss illustrate differing fabrics and conditions, but no universal thermometer can be read from a name without considering composition and history. Contact metamorphism near an intrusion and regional metamorphism during tectonic burial produce different spatial evidence.

For a simple uniform overburden, pressure P=ρgz. Use density 2700 kg/m³, gravitational acceleration 9.81 m/s² and depth in metres; divide pascals by one million for MPa. The separate supplied temperature path is T=15+Gz with G in °C/km and depth in kilometres.

This lithostatic pressure is an approximately direction-independent load, not the differential stress responsible for a particular foliation. Linear gradients are teaching paths, not measured geothermal profiles or mineral-stability diagrams. A real interpretation must compare mineral reactions, composition, fluids and possible melting boundaries rather than assigning a rock name from these two numbers alone.

3. Reconstruct a worked example

At 15 km and 25 °C/km, pressure is 397.305 MPa and temperature 390 °C. A 35 °C/km path at the same depth has the same load pressure but temperature 540 °C.

4. Predict and investigate

Predict first: Can equal-depth rocks differ in temperature without differing in load pressure?

5. Test a changed case

Apply the mechanism to a changed case

At 20 km and 15 °C/km, calculate pressure and temperature. Does pressure alone prove foliation?

Retain the calculation, evidence and assumptions before opening public feedback.

Compare a worked response

Pressure is 529.74 MPa and temperature 315 °C. Pressure alone does not establish differential stress, suitable minerals or time for a foliated fabric.

6. Retain evidence and its limits

Keep the first prediction, complete ledger, changed case and rejected alternative in the lesson notebook. Supplied observations and bounded CPU models are not actual specimen handling, fieldwork or independently assessed competence. Record source purpose and uncertainty rather than treating public feedback as independent reasoning.

Mechanism and classification reference, checked 30 October 2026. Original teaching prose, numerical packets and questions; no source illustration or exercise is copied.

Apply

Public practice checks a specific claim. It does not establish independent mastery.

At 20 km and 15 °C/km, calculate pressure and temperature. Does pressure alone prove foliation?

Your explanation and limitations

Continue

Completion requires a saved prediction, at least one capture and a reflection. Presence checks do not grade your reasoning.

Skipping retains experiments and awards no mastery.

Previous: Connect sedimentary texture to compaction and cementation Next: Discriminate competing rock histories using relationships

Save a science backup or import one

Science work is stored locally in this browser, separately from mathematics and AI. It does not sync automatically. Use this science-only backup; this checkout's older all-subject export does not include science.

A legacy file is available only when the complete snapshot fits the 36 MB limit. For larger snapshots, prepare a complete file set below; never discard notebooks to make a smaller file.

Choose a science backup (maximum 36 MB)

Matching imported notebook drafts replace their current drafts. Omitted lessons and known first attempts remain. Export your current work first if you want to retain both drafts.

Complete file sets and course backups

A file set can hold more work than one science file. Keep its manifest and every part together. Each file is limited to 36 MB. This format needs this version of LearnAI or a compatible newer version; older versions can use only the legacy single-file backup above.

Export scope

The set includes every saved science course and global continuation at this moment. Later edits need a new export. A conflicting tab exports its own visible work, which may differ from saved work in another tab.

Choose the manifest and all parts together

0 file(s) selected. File order and filenames do not determine identity. Missing, changed or conflicting parts block the entire restore; no good part is applied by itself.

Science storage: loading. No account or remote computation is required.