| A | B |
|---|
| Seismic wave | Vibrations that travel through Earth - they carry energy |
| Crust | The layer of rock the forms Earth's outer surface |
| Mantle | The layer of hot, solid material between Earth's crust and core |
| Lithosphere | A rigid layer made up of the uppermost part of the mantle and the crust. |
| Asthenosphere | The soft layer of the mantle on which the lithosphere floats |
| Outer Core | A layer of molten iron and nickel that surrounds the inner core of Earth |
| Inner Core | A dense sphere of solid iron and nickel at the center of Earth |
| Continental drift | The hypothesis that the continents slowly move across Earth's surface |
| Pangaea | The name of the single landmass that broke apart 200 million years ago and gave rise to today's continents |
| Fossil | a trace of an ancient organism that has been preserved in rock |
| stress | a force that acts on rock to change its shape or volume |
| Plate | A section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust. |
| Fault | A break in Earth's crust where masses of rock slip past each other |
| Plate tectonics | The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle. |
| Divergent Boundary | A plate boundary where two plates move away from each other |
| Rift Valley | A deep valley that forms when two plates move apart |
| Convergent Boundary | A plate boundary where two plates move towards each other |
| Tension | Stress that pulls on the crust and pulls the rock apart so it becomes thinner in the middle |
| Compression | Stress that squeezes or pushes rock together until it folds or breaks |
| Shearing | Stress that pushes rock in opposite directions |
| Transform Boundary | a plate boundary where two plates move past each other in opposite directions |
| Earthquake | The shaking that results from the movement of rock beneath Earth's surface. |
| P wave | A type of seismic wave that compress and expand the ground (like a slinky) |
| S wave | A type of seismic wave that moves the ground up and down or side to side |
| focus | The point beneath Earth's surface where rock breaks under stress and causes an Earthquake. |
| epicenter | The point on Earth's surface directly above an earthquake's focus. |
| seismograph | a tool/device that records ground movement caused by seismic waves |
| richter scale | A scale that rates an earthquake's magnitude based on the size of its seismic wave |
| magma chamber | The pocket beneath a volcano where magma collects |
| lava flow | The area covered by lava as it pours out of a volcano's vent. |
| dormant | describes a volcano that is not currently active, but that may become active in the future |
| active | describes a volcano that is likely to erupt soon |
| extinct | describes a volcano that is no longer active and is unlikely to ever erupt again |
| crater | a bowl-shaped area that forms around a volcano's central opening |
| pipe | A long tube in a volcano where magma moves from the magma chamber to Earth's surface |
| vent | The opening in a volcano where molten rock and gas leave a volcano |
| caldera | A large hole that is formed when the roof of the magma chamber collapses |
| magma | The molten mixture of rock-forming substances, gases, and water from the mantle |
| surface wave | When P waves and S waves reach the surface of Earth |
| volcano | A weak spot in the crust where magma has come to the surface |
| ring of fire | The area around the Pacific ocean that experiences volcanoes and major earthquakes |
| lava | liquid magma that reachers the surface |
| hotspot | An area where magma from deep within the mantle melts through the crust above it |
| sedimentary | A type of rock that forms when parts of other rocks or plants/animals are pressed and cemented together. |
| metamorphic | A type of rock that forms from an existing rock that is changed by heat, pressure or chemical reactions.. |
| igneous rock | A type of rock that forms from the cooling of molten rock at or below the surface. |
