Earth’s Interior & Plate Tectonics Mind Map
← Earth’s Interior & Plate TectonicsEarth’s layers, how scientists study them with seismic waves, and how moving plates cause earthquakes and volcanoes.
- crustEarth’s thin, rocky outer layer.We live on the crust.
- mantleThe thick layer of hot rock between the outside layer and the core. Parts of it flow very slowly.The mantle makes up most of Earth’s volume.
- outer coreThe layer of liquid iron and nickel around Earth’s center.Moving metal in the outer core creates Earth’s magnetic field.
- inner coreEarth’s solid, very hot center, made mostly of iron and nickel.Huge pressure keeps the inner core solid.
- lithosphereEarth’s rigid outer shell, made of the crust and the rigid uppermost mantle.The lithosphere is broken into plates.
- asthenosphereA region of mostly solid upper-mantle rock that deforms and flows slowly beneath the rigid plates.Plates slide over the asthenosphere.
- densityHow much mass is packed into a certain volume.Iron in the core has a high density.
- seismic wavesWaves of energy that travel through Earth, usually from an earthquake.Seismic waves bend when they enter a new layer.
- P waveA fast seismic wave that pushes and pulls rock. It can travel through solids and liquids.The P wave reached the station first.
- S waveA slower seismic wave that shakes rock side to side. It cannot travel through liquid.No S wave passed through the outer core.
- seismographAn instrument that records ground shaking from seismic waves.The seismograph drew tall zigzags during the quake.
- plate tectonicsThe theory that Earth’s outer shell is broken into large pieces that move slowly.Plate tectonics explains why earthquakes happen where they do.
- tectonic plateOne large piece of Earth’s rigid outer shell.North America sits on a tectonic plate.
- continental driftThe idea that the continents slowly move across Earth’s surface.Matching fossils on two continents support continental drift.
- PangaeaA supercontinent that included all the land on Earth about 300 million years ago.Africa and South America were joined in Pangaea.
- convection currentA circulation of fluid driven by density differences: less dense material rises and denser material sinks under gravity.A convection current in the mantle can drag a plate along.
- sea-floor spreadingNew ocean floor forming where plates pull apart and magma rises.Sea-floor spreading makes the Atlantic Ocean wider each year.
- mid-ocean ridgeA long underwater mountain chain where plates pull apart and new ocean floor forms.Iceland sits on top of a mid-ocean ridge.
- divergent boundaryA place where two plates move apart.A divergent boundary runs down the middle of the Atlantic.
- convergent boundaryA place where two plates push together.The Himalayas formed at a convergent boundary.
- transform boundaryA place where two plates slide past each other.The San Andreas Fault is a transform boundary.
- subductionOne plate sinking beneath another into the mantle.Subduction along the coast feeds a chain of volcanoes.
- trenchA deep, narrow valley in the ocean floor where one plate sinks under another.The Mariana Trench is the deepest place in the ocean.
- faultA crack in Earth’s crust where rocks have moved.The New Madrid fault runs under the central United States.
- earthquakeShaking of the ground caused by rocks suddenly moving along a crack in the crust.The earthquake knocked books off the shelves.
- volcanoAn opening in Earth’s crust where magma, gas, and ash come out.Mount St. Helens is a volcano in Washington.
- tsunamiA series of long waves caused by sudden displacement of water, often during an undersea earthquake.A tsunami can cross a whole ocean in a day.
- Ring of FireThe belt of earthquakes and volcanoes around the edge of the Pacific Ocean.Japan is part of the Ring of Fire.
- hot spotA region of persistent volcanism often supplied by unusually hot mantle material; it can occur away from plate boundaries.The Hawaiian Islands formed over a hot spot.