Guided Exploration: Plate Tectonics
What is Plate Tectonics?
1. Bronze Globe
Observe this model to explore the solid Earth — what the Earth looks like without water. (To understand the term “solid Earth,” watch the Dynamic Earth sphere overhead and see the liquid slowly drained away from the rocky surface). Compare the familiar topography of the continents with the less familiar topography of the ocean basins. Then look at the “slice of crust” model hanging overhead. Use the diagram below to find the region on the globe that’s represented in the model above. In this part of the hall, you’ll be exploring the ways in which plate tectonics shapes the solid Earth.
Wallace Gilroy Bronze Earth model
2. Churning Earth Section
Convection is the main way in which heat is lost from the interior of the Earth. It’s the force that drives the movement of tectonic plates. Go to the video kiosk in the circular table and watch scientific models of how the Earth’s core and mantle convect.
The churning Earth
The churning Earth
When Plates Collide3. Model of Collision
When an oceanic plate meets a continental plate, the oceanic plate descends, or subducts, beneath the continental plate and sinks into the mantle. Explore the model and use your hands to simulate how plates collide.
Where plates collide
4. Explosive Volcanism Section
Explore why most explosive eruptions occur in volcanoes above subduction zones. Examine samples from Medicine Lake Volcano, California (#5-10), and watch a video of scientists at work in Indonesia.
Explosive volcanism
Volcanic bombs
Basalt tablet
Deposits from an explosive eruption
Pumice
Obsidian
Remnants of a buried forest
5. Mountain Formation Section
When two continental plates meet, one is thrust over the other to form mountain ranges like the Alps and the Himalayas. Watch the video and examine the sand model, and think about how the model helps scientists understand the way plates interact to form mountain ranges. Then observe the rock samples (#1-7) that illustrate the processes (uplifting, folding, crustal thickening, and faulting).
Mountain building
Modeling mountain building
Barrovian sequence
Ultra-high pressure rock
Gore Mountain garnet
Eclogite
A fold in a rock
Deformed conglomerates
Deforming rocks in the laboratory
When Plates Move Past Each Other6. Model of Slip
A fault forms when oceanic or continental plates slide past each other in opposite directions, or move in the same direction but at different speeds. Explore the model and use your hands to simulate how plates move past each other.
When plates move past each other
7. Earthquakes Section
Earthquakes occur along fault lines (cracks near plate boundaries where the crust on opposites sides moves). Explore the earthquake video kiosk and associated text panels to find out how monitoring helps scientists estimate the odds of an earthquake taking place within a certain period of time. Then find the faults on the two large casts and the samples (#1-2) and examine what they tell us.
Earthquakes
Fault in Crystalline rock
Which way does a fault move?
When Plates Separate8. Model of Separation
Most spreading plate boundaries are found in ocean basins. Explore the model and use your hands to simulate how plates separate.
Where plates separate
9. Basalts
Most volcanoes erupt basalt, a fluid lava from the mantle that forms flows. Most basalt erupts from cracks in the seafloor, but some basaltic lava flows occur on continental crust. Compare the shapes of the underwater (#9-17) and flood basalts (#18), and explore their formation.
Glassy buds
East Pacific Rise pillow basalt
Lava pillars
Deep-ocean pillow basalt
Pillow andesite from a lake
Mid-Atlantic Ridge pillow basalt
Pacific Ocean pillow basalt
East Pacific Rise pillow basalt
Columns of lava
When Plates Move10. Hawaiian Hot Spots
Basaltic lava also erupts at hot spots, where molten rock, or magma, forms in plumes of hot rock that rise from deep in Earth to penetrate a moving plate above. Watch the video and explore the various specimens. What does the pattern of the Hawaiian island chain reveal about how the Pacific plate is moving?
The Hawaiian hot spot
Wrap Up
11. Bronze Globe: Revisit the globe and connect specific specimens to places on the globe and to the tectonic processes at work behind them. (Examples: Collide — Andes and Himalayas; Separate — Mid-Atlantic Ridge; Slip — San Andreas fault)