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Tectonics Grade 9 Science

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  • How does subduction occur?
    A denser plate sinks beneath a less dense plate
    Two plates move side by side
    Two plates push apart
  • Which layer of the Earth contains the tectonic plates?
    The inner core
    The crust
    The outer core
  • How often does Earth’s magnetic field reverse?
    Every few thousand to million years
    Never
    Every 100 years
  • Which force is responsible for pulling tectonic plates apart at mid-ocean ridges?
    Ridge push
    Mantle pressure
    Slab pull
  • Why do tectonic plates float on the mantle?
    Because they contain water
    Because they are made of solid rock
    Because they are less dense than the mantle
  • What happens when two continental plates collide?
    A volcano forms
    Mountains form
    A trench is created
  • How does new oceanic crust form?
    From the sinking of tectonic plates
    From magma rising at mid-ocean ridges
    From melting of old rocks
  • What evidence supports the theory of plate tectonics?
    Matching fossils on different continents
    The movement of clouds in the sky
    The presence of water in oceans
  • What happens at a transform plate boundary?
    Plates collide
    Plates move apart
    Plates move past each other
  • What happens at a convergent boundary?
    Plates collide
    Plates move apart
    Plates slide past each other
  • What is seafloor spreading?
    The sinking of oceanic crust
    The gradual widening of ocean basins
    The closing of oceanic trenches
  • What is the significance of magnetic mineral alignment in rocks?
    It records the direction of Earth’s magnetic field at the ti
    It determines the color of the rock
    It makes the rock lighter
  • What happens to magma as it cools and solidifies?
    It forms igneous rock
    It becomes a gas
    It turns into sedimentary rock
  • What happens to old oceanic crust?
    It turns into mountains
    It remains on the surface forever
    It subducts into the mantle
  • Which feature is created at a divergent plate boundary?
    Deep-sea trenches
    Fold mountains
    Mid-ocean ridges
  • How do magnetic stripes provide evidence for seafloor spreading?
    They indicate the presence of large animals
    They are unrelated to tectonic activity
    They show a record of Earth's changing magnetic field
  • What drives convection currents in the mantle?
    Heat from the Earth's core
    The rotation of the Earth
    The heat from the Sun
  • Which statement is true about convection currents?
    Cold mantle material rises to the surface
    Hot mantle material rises, cools, then sinks
    The mantle does not move
  • What do normal and reversed magnetic stripes show?
    The age of oceanic crust and changes in Earth’s magnetic fie
    The depth of the ocean
    The speed of tectonic plate movement
  • Where is the youngest oceanic crust found?
    Near mid-ocean ridges
    At subduction zones
    Near the continents
  • What do reversed magnetic stripes on the ocean floor indicate?
    The Earth's magnetic field has changed over time
    The ocean floor is sinking
    The crust is eroding
  • Why do older oceanic plates subduct under younger ones?
    They are denser
    They are thicker
    They are heavier due to water
  • What causes the movement of tectonic plates?
    Wind currents in the atmosphere
    Convection currents in the mantle
    Earth’s gravitational pull
  • What happens when magnetic minerals in magma cool and solidify?
    They align with Earth's magnetic field
    They disappear
    They become radioactive
  • What is the role of convection currents in seafloor spreading?
    They stop plate movement
    They pull continents together
    They push magma up to create new crust
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