Earth's Layers and Plate Tectonics Flashcards

Grade 9 · Science · Flashcards

Study Earth's interior structure and plate tectonics with these 12 essential flashcards.

Flashcards

Inner Core: Earth's solid center made of iron-nickel; temperatures ~5,000°C; solid due to extreme pressure.
Outer Core: Liquid iron-nickel layer surrounding the inner core; generates Earth's magnetic field.
Mantle: Thickest layer of Earth (~2,900 km); semi-solid rock; convection currents here drive plate tectonics.
Crust: Earth's thin outermost layer; oceanic crust is thin and dense (basalt); continental crust is thick and less dense (granite).
Lithosphere: The rigid outer shell of Earth = crust + upper mantle; divided into tectonic plates.
Tectonic Plates: Large pieces of lithosphere that move slowly (cm/year) driven by mantle convection currents.
Convergent Boundary: Plates move toward each other; forms mountains, volcanoes, or deep ocean trenches via subduction.
Divergent Boundary: Plates move apart; magma rises to form new crust; creates mid-ocean ridges and rift valleys.
Transform Boundary: Plates slide horizontally past each other; produces earthquakes; no crust created or destroyed.
Subduction: Dense oceanic plate sinks beneath less dense plate at convergent boundary, forming a trench.
Seafloor Spreading: Process at divergent boundaries where new oceanic crust is created as magma rises and solidifies.
Ring of Fire: Zone around the Pacific Ocean where ~90% of earthquakes and ~75% of volcanoes occur; marks Pacific Plate boundaries.