Hartford Basin Rift & Dinosaur Tracks Modeler
Overview
How did dinosaur tracks made in the mud 200 million years ago survive to be discovered today in Rocky Hill, Connecticut? In this activity, you will model the geologic history of the Hartford Basin, balancing tectonic rifting, sedimentation, volcanic eruptions, and glacial erosion.
Estimated Time: 45-60 minutes Materials: Computer with internet access, Simulation: Hartford Basin Rift & Dinosaur Tracks Modeler
Anchoring Phenomenon
In 1966, an excavator in Rocky Hill, Connecticut accidentally uncovered a sandstone slab containing thousands of dinosaur footprints. These tracks, assigned to the ichnogenus Eubrontes (likely made by a Dilophosaurus-like theropod), were made in soft mud near a lake 200 million years ago. But how did soft footprints survive millions of years, multiple tectonic events, and miles-thick glaciers, only to be found perfectly preserved just inches below the modern surface?
5E Lesson Plan
1. Engage: The Impossible Footprints
Watch a video or review photos of Dinosaur State Park in Connecticut. Consider the following:
- Footprints are made in soft mud. What usually happens to footprints in mud after a few days or weeks?
- What forces would need to act on these footprints to turn them into solid rock and protect them for 200 million years?
- If they were buried deep underground to be preserved, how did they end up right at the surface for a bulldozer to find?
2. Explore: Modeling the Basin
Open the Hartford Basin Rift Modeler simulation. Your goal is to find the precise sequence of events and parameters that allows the footprints to be preserved and then exposed at the surface.
Procedure:
- Epoch 1: Triassic Breakup. Pangea begins to rift. Adjust the Eastern Border Fault Angle (40°-80°) and Rift Extension (1-5 km). Click Simulate. Observe the formation of the half-graben basin.
- Epoch 2: Early Jurassic Deposition. Set the Sediment Deposition Rate (0.3-1.0). Click Simulate. The basin fills with lakes and sediment. Dinosaurs leave tracks on the muddy shores.
- Epoch 3: CAMP Volcanism. Set the Basalt Flow Thickness (20-100 m). Click Simulate. Flood basalts cover the landscape, burying the sediment. The entire block tilts.
- Epoch 4: Pleistocene Glaciation. Set the Erosion Depth (0-100). Click Evaluate Discovery. Glaciers scrape the surface.
- Iterate: If the tracks are destroyed or remain buried, you fail. Click Play Again and adjust your parameters until you successfully expose the tracks!
Data Collection: Record your attempts in the table below. Note what happened (e.g., “Eroded too much,” “Not enough basalt,” “Success!”).
| Attempt | Fault Angle (°) | Extension (km) | Sediment Rate | Basalt Thickness (m) | Erosion Depth | Result |
|---|---|---|---|---|---|---|
| 1 | _____ | _____ | _____ | _____ | _____ | _________ |
| 2 | _____ | _____ | _____ | _____ | _____ | _________ |
| 3 | _____ | _____ | _____ | _____ | _____ | _________ |
3. Explain: Constructive and Destructive Forces
Based on your successful model, answer the following:
- Internal Processes: How did tectonic rifting and volcanism act as constructive forces in this model? What did they build or create?
- Surface Processes: How did sedimentation and glacial erosion act as destructive or modifying forces?
- Scale: Compare the temporal (time) scale of the basalt eruption versus the glacial erosion. Which happened faster? How did their spatial scales differ?
4. Elaborate: Feedback and Protection
- The Protective Cap: Why was the Holyoke Basalt layer necessary for the preservation of the tracks? What would have happened to the sedimentary rock (East Berlin Formation) during the Pleistocene glaciation if the basalt hadn’t erupted?
- The Tilt: How did the tectonic tilting of the basin (during Epoch 3) make it possible for glaciers to expose the tracks without eroding the entire sedimentary layer?
5. Evaluate: The Geologic Story
Deliverable: Create a 4-panel comic strip, flowchart, or short narrative explaining the history of the Rocky Hill dinosaur tracks.
- You must include the specific processes: Rifting, Sedimentation, Volcanism, and Glacial Erosion.
- You must identify which processes are internal vs. surface processes.
- You must explain the sequence and relative timing of these events.
Teacher Notes
NGSS Alignment
- 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 (Develop a model based on evidence to illustrate the relationships between systems or between components of a system).
- Disciplinary Core Idea: ESS2.B: Plate Tectonics and Large-Scale System Interactions (Plate movements are responsible for most continental… features).
- Crosscutting Concept: Stability and Change (Change and rates of change can be quantified and modeled over very short or very long periods of time).
Evidence of Learning
Student work should demonstrate the following evidence statements for HS-ESS2-1:
- Components of the model: Students document the variables (Fault Angle, Extension, Sediment Rate, Basalt Thickness, Erosion Depth) and identify internal processes (volcanism/rifting) and surface processes (sedimentation/erosion).
- Relationships: Students describe how internal processes built the basin and preserved the tracks (basalt cap), while surface processes filled the basin (sediment) and later wore it down (glacial erosion).
- Scale: In the ‘Explain’ section, students differentiate the temporal scales of these events (rapid volcanism vs. slow sedimentation and eventual glacial erosion millions of years later).