Earth's Layers and Plate Tectonics Flashcards

Grade 10 · Science · Flashcards

Study key terms and concepts for Earth's internal structure and plate tectonics.

Flashcards

Crust: Earth's thin outermost layer; either continental (granite, ~35 km thick) or oceanic (basalt, ~7 km thick).
Mantle: The thick layer of semi-solid silicate rock between the crust and core; convection here drives plate movement.
Outer core: Liquid iron-nickel layer surrounding the inner core; convection generates Earth's magnetic field.
Inner core: Solid iron-nickel center of Earth; under immense pressure despite extreme temperature (~5,000–6,000°C).
Lithosphere: The rigid outer layer of Earth (crust + uppermost mantle); divided into tectonic plates.
Asthenosphere: Semi-fluid upper mantle on which lithospheric plates move; deforms slowly under heat and pressure.
Convergent boundary: Where two plates collide; forms mountains (continent-continent) or trenches and volcanoes (ocean-continent).
Divergent boundary: Where two plates move apart; forms mid-ocean ridges (underwater) or rift valleys (on land).
Transform boundary: Where plates slide horizontally past each other; causes earthquakes (e.g., San Andreas Fault).
Subduction zone: Where dense oceanic crust dives under another plate into the mantle; associated with trenches and volcanic arcs.
Seafloor spreading: Creation of new oceanic crust at divergent boundaries as magma wells up and solidifies.
Continental drift: Wegener's hypothesis (1912) that continents were once joined as Pangaea and have since moved apart.