Teacher Notes

NGSS Alignment

This task is aligned to the following NGSS dimensions and Performance Expectation:

• Performance Expectation: HS-ESS2-1. Develop a model to illustrate how Earth’s internal and surface processes operate at different spatial and temporal scales to form continental and ocean-floor features.
• Science and Engineering Practice: Developing and Using Models. Students develop a model based on evidence to illustrate the relationships between components of a system.
• Disciplinary Core Ideas:
  • ESS2.A: Earth Materials and Systems (Interacting dynamic systems).
  • ESS2.B: Plate Tectonics and Large-Scale System Interactions (Plate movements are responsible for continental features).
• Crosscutting Concept: Stability and Change. Change and rates of change can be quantified and modeled over very long periods of time.

Evidence Statements Addressed

Students will demonstrate their understanding by meeting the following evidence statements for HS-ESS2-1:

1. Components of the model: Students identify and describe descriptions and locations of specific continental features (the Metacomet Ridge vs. the brownstone valley). Students identify internal processes (volcanism, rifting) and surface processes (weathering, erosion), along with a temporal scale.
2. Relationships: Students describe the relationships, specifically that internal processes (volcanism/rifting) are causal agents in building up Earth’s surface (the basalt layers), and surface processes (erosion/glaciation) are causal agents in wearing it down differentially based on rock hardness.
3. Connections: Students use the model to illustrate the relationship between the formation of the continental features (steep basalt ridges and flat valleys) and the internal/surface processes operating over 200 million years.

The Metacomet Ridge Puzzle

Part 1: Engage (Anchoring Phenomenon)

If you drive through central Connecticut near Middletown, you will notice a striking contrast in the landscape. While much of the land is relatively flat and composed of soft, reddish-brown sandstone (often called “brownstone”), there are sudden, dramatic, steep cliffs that rise hundreds of feet into the air facing west (such as Higby Mountain and Beseck Mountain). These cliffs are made of a very hard, dark rock called basalt (or “trap rock”).

Why do these hard basalt cliffs suddenly appear in the middle of a softer brownstone valley? What forces over millions of years created this specific landscape?

Part 2: Explore (Simulation Investigation)

Estimated Time: 20-30 minutes Materials: Computer with internet access, Metacomet Ridge Simulation.

You will use a geological simulation to trace the history of this region over the last 200 million years.

Instructions:

1. Open the simulation. Read the “Current Process” description for the initial state (Pangaea).
2. Click the buttons in chronological order (1 through 5) to advance geologic time.
3. After each step, carefully observe the changes in the cross-section diagram (the canvas). Look at the key to identify rock types (Pre-existing Metamorphic, Brownstone, Basalt, Magma).
4. Record your observations in the data table below.

Data Collection Table

Part 3: Explain (Sensemaking)

Use your observations from the simulation to answer the following questions:

1. Constructive Forces (Building Up): Which steps in the simulation represented internal Earth processes that brought new material to the surface? What specific type of rock was formed by this process? _____

2. Destructive Forces (Wearing Down): In Step 5 (Erosion & Glaciation), both the brownstone and the basalt were subjected to the same erosional forces (water, ice). Did they erode at the same rate? Use evidence from the final simulation image to explain why the landscape looks the way it does. _____

Part 4: Elaborate/Evaluate (Argumentation & Modeling)

Student Deliverable: Write a final scientific explanation that answers our original question: Why do the hard basalt cliffs of the Metacomet Ridge suddenly appear in the middle of a softer brownstone valley?

Your explanation must include:

• How the internal processes (rifting and volcanism) operated 200 million years ago to create the different rock layers.
• How the surface processes (weathering and erosion) operated over the subsequent millions of years.
• An explanation of how the differing hardness of the rock types caused differential erosion, resulting in the specific ridge and valley features we see today.

Extension: How might this landscape change over the next 200 million years if erosion continues without any new volcanic activity?