Grade 8 Science Vocabulary
Earth’s Interior & Plate Tectonics
Earth’s layers, how scientists study them with seismic waves, and how moving plates cause earthquakes and volcanoes.
Ohio science standards in this unit
- 8.ESS.1 · Earth’s interiorThe composition and properties of Earth's interior are identified by the behavior of seismic waves.
- 8.ESS.2 · Plate tectonicsEarth's lithosphere consists of major and minor tectonic plates that move relative to each other.
Definitions are written in plain language to support WIDA's Standard 4 (Science) English Language Development standard.
Practice 36 words
Flashcards
Flip through each word and its meaning.
Start
Drag-and-Drop Match-Up
Drag each word onto its meaning.
Start
Multiple Choice Quiz
Choose the correct meaning for each word.
Start
Type the Term
Read a meaning and type the word.
Start
Sort It Out
Sort the words by topic.
Start
Find the Word
Search for the unit’s words in a letter grid.
Start
Crossword Puzzle
Solve a crossword using the meanings as clues.
Start
Spelling Practice
Hear each word, then spell it.
Start
Pronunciation Practice
Hear each word and practice saying it.
Start
Study guide
Earth’s interior (8.ESS.1)
- refraction
- The bending of a wave as it moves from one material into another.
- reflection
- When a wave bounces off a surface.
- seismic waves
- Waves of energy that travel through Earth, often caused by earthquakes.
- inner core
- Earth’s center: a solid ball of iron and nickel.
- outer core
- A layer of liquid iron and nickel around the inner core.
- upper mantle
- The top part of the mantle. Some of it moves slowly like very thick putty.
- lower mantle
- The hot, solid, deepest part of the mantle, above the outer core.
- crust
- Earth’s thin, rocky outer layer.
- gravitational energy
- Energy from gravity pulling material together. It helped heat early Earth.
- radioactive elements
- Elements whose atoms break down and give off energy. They help keep Earth’s inside hot.
- convection currents
- Circles of moving material: hot material rises, cools, and sinks again.
- planetary differentiation
- How early Earth separated into layers, with heavy materials sinking to the center.
- energy transfer
- When energy moves from one object or place to another.
- energy transformation
- When energy changes from one form to another.
Plate tectonics (8.ESS.2)
- tectonic plates
- Huge pieces of Earth’s lithosphere that fit together like puzzle pieces and slowly move.
- paleomagnetism
- The record of Earth’s past magnetic field saved in rocks.
- continental drift
- The idea that the continents were once joined and have slowly moved apart.
- sea-floor spreading
- When new ocean floor forms at mid-ocean ridges and pushes older floor away.
- divergent boundary
- A place where two plates move apart.
- convergent boundary
- A place where two plates push toward each other.
- transform boundary
- A place where two plates slide past each other.
- subduction zone
- A place where one plate sinks under another plate into the mantle.
- Alfred Wegener
- The scientist who proposed continental drift in 1912.
- Arthur Holmes
- A geologist who suggested that mantle convection could move the continents.
- Harry Hess
- A scientist who proposed sea-floor spreading in the early 1960s, working alongside Robert Dietz’s similar idea.
- volcanic activity
- Magma, gas, and ash coming up through openings in Earth’s crust.
- earthquake
- Sudden shaking of the ground when rocks break and move along a fault.
- tsunami
- A giant ocean wave, usually caused by an earthquake under the sea.
- geyser
- A hot spring that shoots hot water and steam into the air from time to time.
- fault
- A crack in Earth’s crust where rocks have moved.
- fold
- A bend in rock layers caused by pressure.
- intrusion
- Magma that pushes into rock layers and hardens underground.
- hydrothermal vent
- A crack in the ocean floor where very hot, mineral-rich water comes out.
- island arc
- A curved chain of volcanic islands formed where one ocean plate sinks under another.
- hot spot
- A place where magma rises from deep in the mantle, far from plate boundaries, like Hawaii.
- rift valley
- A long, low valley that forms where plates pull apart.
Warm-up words to review
Words from earlier grades that help with this unit.
- heat
- Thermal energy moving from a warmer object to a cooler one.
- igneous rock
- Rock that forms when magma or lava cools and hardens.
- metamorphic rock
- Rock changed by heat and pressure without melting.
- sedimentary rock
- Rock made of layers of sediment pressed and cemented together.
- magma
- Melted rock below Earth’s surface.
- thermal energy
- The energy of moving particles in a substance.
- radiation
- Energy that travels as waves, even through empty space.
- convection
- Heat moving through a liquid or gas as warm material rises and cool material sinks.
- conduction
- Heat moving by direct touch from one thing to another.