Plate Tectonics Flashcards
Grade 7 · Science · Flashcards
Key terms for tectonic plates, plate boundaries, and Earth's interior layers.
Flashcards
- Tectonic plate
- One of about 15 rigid sections of Earth's lithosphere that slowly moves over the asthenosphere.
- Lithosphere
- Earth's outermost rigid layer, including the crust and upper mantle; broken into tectonic plates.
- Asthenosphere
- The partially molten, slow-flowing layer of upper mantle on which plates move.
- Convection current
- Circular movement of material driven by heat; the engine that moves tectonic plates.
- Divergent boundary
- Where two plates move apart; new crust forms from rising magma. Example: Mid-Atlantic Ridge.
- Convergent boundary
- Where two plates collide; can form mountains, trenches, or volcanoes depending on plate types.
- Transform boundary
- Where plates slide sideways past each other; causes earthquakes. Example: San Andreas Fault.
- Subduction
- When a denser plate dives beneath a lighter one at a convergent boundary.
- Subduction zone
- Area where subduction occurs; associated with deep trenches and volcanic arcs.
- Pangaea
- Supercontinent that existed ~225 million years ago; all present-day continents were once joined.
- Continental drift
- The gradual movement of continents over Earth's surface over millions of years.
- Seafloor spreading
- Process at divergent boundaries where new oceanic crust is created as plates move apart.
- Mid-ocean ridge
- Underwater mountain chain at a divergent boundary where new seafloor forms continuously.
- Fault
- A crack in Earth's crust along which blocks of rock move relative to each other.
- Alfred Wegener
- German scientist who first proposed the theory of continental drift in 1912.
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