Mantle Convection Explorer Task
Estimated Time: 45 - 60 minutes
Materials: Computer/tablet with internet access, notebook or paper for data collection.
Teacher Notes & Alignment
This inquiry-based task is aligned with the Next Generation Science Standards (NGSS).
- Performance Expectation: HS-ESS2-3: Develop a model based on evidence of Earth’s interior to describe the cycling of matter by thermal convection.
- Science and Engineering Practice (SEP): Developing and Using Models. Students develop a model based on evidence to illustrate the relationships between systems or between components of a system.
- Disciplinary Core Idea (DCI): ESS2.A: Earth Materials and Systems. Motions of the mantle and its plates occur primarily through thermal convection, which involves the cycling of matter due to the outward flow of energy from Earth’s interior and gravitational movement of denser materials toward the interior.
- Crosscutting Concept (CCC): Energy and Matter. Energy drives the cycling of matter within and between systems.
Evidence Statements: Students will demonstrate understanding by developing a model that shows:
- Components of the model: Earth’s interior in cross-section and radial layers determined by density; the plate activity in the outer part of the geosphere; radioactive decay and residual thermal energy as a source of energy; heat loss at the surface; and the process of convection causing hot matter to rise and cool matter to sink.
- Relationships: Thermal energy from radioactive decay and residual heat from Earth’s formation provides energy that drives the flow of matter in the mantle; thermal energy is released at the surface as new crust forms and cools; flow of matter by convection in the solid mantle exerts forces on crustal plates, causing them to move; matter is cycled between the crust and mantle at plate boundaries.
- Connections: The model connects the flow of matter in the mantle to the movement of crustal plates, radial layers determined by density, and the addition of significant thermal energy released by radioactive decay.
Part 1: Engage
Anchoring Phenomenon: Seismic waves allow scientists to create maps of Earth’s three-dimensional structure. These maps show that Earth’s mantle isn’t perfectly uniform, but instead has massive regions of hot, less dense rock rising up, and cooler, denser rock sinking down. This movement of rock deep beneath our feet is what drives the massive tectonic plates at the surface to drift, collide, and tear apart.
Questions:
- What forces might cause solid rock to flow like a thick liquid?
- How can heat deep inside the Earth cause massive continents on the surface to move? ___ _______
Part 2: Explore
You will use the Mantle Convection Explorer simulation to investigate these questions.
Instructions:
- Open the simulation. Take a moment to familiarize yourself with the interface:
- Core Temperature Slider: Controls the heat at the bottom (Core-Mantle Boundary).
- Mantle Viscosity Slider: Controls how “runny” or “stiff” the mantle rock is.
- Interaction Tools: Allow you to “Add Heat” (red button) or “Add Cool” (blue button).
- Show Vectors: Checkbox to show arrows representing the direction and speed of flowing rock.
- Initial Observation: Set Core Temperature to “Low” and Mantle Viscosity to “Medium”. Observe the density (temperature) field and the plate movement at the top. Record your observations in the table below.
- Investigate Temperature: Increase the Core Temperature to “High”. Describe what happens to the hot rock (red) and the cool rock (blue). Observe the velocity vectors and the movement of the plates.
- Investigate Viscosity: Reset the simulation. Set Core Temperature to “High”. Change the Mantle Viscosity to “High (Stiff)”. How does this affect the convection currents and plate movement? Change it to “Low (Runny)”. Record the differences.
- Interactive Perturbation: Set Core Temperature and Viscosity to “Medium”. Select the “Add Cool” tool. Click and hold on the lithosphere (top layer) to simulate a subducting, cold oceanic plate. Observe how this “sinking” cold rock affects the mantle flow and the adjacent plates.
Data Collection Table:
| Core Temp | Mantle Viscosity | Observations of Convection Flow | Plate Movement (Speed/Direction) |
|---|---|---|---|
| Low | Medium | _____ | _____ |
| High | Medium | _____ | _____ |
| High | High (Stiff) | _____ | _____ |
| High | Low (Runny) | _____ | _____ |
| Medium | Medium (with Add Cool) | _____ | _____ |
Part 3: Explain
Based on your observations in the simulation:
- Describe the relationship between the core temperature and the rate of convection in the mantle. Why does hot rock rise and cool rock sink? _____
- Explain how the convection currents in the mantle cause the tectonic plates at the surface to move. _____
- How does the “viscosity” of the mantle affect the speed of plate movement? _____
Part 4: Elaborate/Evaluate
Deliverable: Develop a conceptual model (a diagram with a written explanation) that describes the cycling of matter by thermal convection in Earth’s interior.
Your model must include:
- Earth’s interior in cross-section (core, mantle, crust/plates).
- The source of thermal energy (the core).
- Arrows showing the direction of convection currents (hot matter rising, cool matter sinking).
- How the convection currents exert forces on the crustal plates, causing them to move.
- A written paragraph explaining the relationships between the components of your model.
Extension: Imagine a hypothetical planet similar to Earth, but its core has completely cooled down. How would the lack of thermal convection affect the surface of that planet over millions of years? What would happen to its tectonic plates?