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Unlock This CourseNow that you've studied plate tectonics throughout this course, it's time to bring everything together! This session will help you review the key concepts, understand how they connect and prepare you for your assessment. Think of Earth's surface like a giant jigsaw puzzle that's constantly moving - that's essentially what plate tectonics is all about.
Key Definitions:
Plate tectonics explains why earthquakes happen, how mountains form and why we find similar fossils on different continents. It's like having the instruction manual for how our planet works! Understanding this theory helps us predict natural disasters and find valuable resources.
Scientists didn't just guess that plates move - they found loads of evidence! Let's review the main types of evidence that support this groundbreaking theory.
Alfred Wegener first proposed continental drift in 1912, but it took decades for scientists to accept his ideas. Here's why his evidence was so convincing:
Identical fossils found on continents separated by vast oceans. For example, Mesosaurus fossils appear in both South America and Africa - but this freshwater reptile couldn't swim across the Atlantic!
Mountain ranges and rock formations match across ocean basins. The Appalachian Mountains in North America align perfectly with similar ranges in Scotland and Scandinavia.
Glacial deposits in tropical regions and coal deposits in Antarctica suggest continents were once in different climate zones.
The Atlantic Ocean is getting wider by about 2-3 centimetres each year - roughly the same rate your fingernails grow! This happens because of seafloor spreading at the Mid-Atlantic Ridge. Iceland sits right on this ridge, which is why it has so many volcanoes and hot springs.
Where tectonic plates meet, exciting things happen! There are three main types of boundaries, each creating different geological features.
These are where plates move apart, like a slow-motion explosion. New crust forms here, making these boundaries constructive.
Underwater mountain ranges where new oceanic crust forms. The Mid-Atlantic Ridge is the most famous example, running down the middle of the Atlantic Ocean like a giant underwater spine.
Here, plates crash into each other like slow-motion car accidents. These are destructive boundaries because crust gets destroyed or deformed.
Creates deep ocean trenches and volcanic island arcs. The Mariana Trench (deepest part of Earth's surface) formed this way.
Forms coastal mountain ranges with volcanoes. The Andes Mountains in South America are a perfect example.
Creates massive mountain ranges without volcanoes. The Himalayas formed when India crashed into Asia.
Plates slide past each other horizontally, like hands rubbing together. These create major fault lines and frequent earthquakes.
California's San Andreas Fault is probably the world's most famous transform boundary. The Pacific Plate moves northwest relative to the North American Plate at about 5cm per year. This movement causes frequent earthquakes, including the devastating 1906 San Francisco earthquake.
But what actually makes these massive plates move? It's all about heat and density differences in Earth's interior.
Hot material rises from deep in the mantle, cools near the surface, then sinks back down. This creates circular currents that drag the plates along, like leaves floating on moving water.
At mid-ocean ridges, newly formed crust is hot and elevated. As it cools and moves away, gravity pulls it downward, pushing the plate forward.
Dense oceanic crust sinks into the mantle at subduction zones, pulling the rest of the plate behind it. This is thought to be the strongest force moving plates.
Understanding plate tectonics helps us predict where natural disasters are most likely to occur. Most earthquakes and volcanoes happen near plate boundaries.
About 90% of earthquakes occur along the "Ring of Fire" around the Pacific Ocean, where several plates meet. Transform boundaries like the San Andreas Fault also produce frequent earthquakes.
Most volcanoes form at convergent and divergent boundaries. Subduction zones create explosive volcanoes, while mid-ocean ridges produce gentler eruptions underwater.
This famous Italian volcano sits where the African Plate subducts beneath the Eurasian Plate. Its explosive eruption in 79 AD buried Pompeii and Herculaneum. The volcano remains active today, threatening millions of people living nearby in Naples.
Ready to ace your plate tectonics assessment? Here are some key strategies and common question types you might encounter.
You'll likely need to identify plate boundaries on maps, explain geological features and predict where hazards might occur. Practice reading geological maps and understanding symbols.
Learn to identify different boundary types from their features: trenches (convergent), ridges (divergent) and fault lines (transform). Remember that most volcanoes and earthquakes occur at plate boundaries.
Be ready to explain how different geological features form. Use proper scientific vocabulary and mention the forces involved (convection, ridge push, slab pull).
You might need to assess how well different pieces of evidence support plate tectonic theory. Remember that multiple lines of evidence make the theory stronger.
Always use specific examples in your answers - examiners love to see real-world applications! Draw simple diagrams to illustrate your points and don't forget to explain the processes, not just describe what happens. Practice timing yourself on past paper questions to build confidence.