| A | B |
|---|
| Geologists | Scientists who study the forces that make and shape planet Earth. |
| Mantle | Layer of hot, solid material between the crust and the core. |
| Crust | Layer of rock that forms Earth's outer skin |
| Lithosphere | A rigid layer made up of uppermost part of the mantle and the crust |
| Asthenosphere | Soft layer below the lithosphere. |
| Core | Consists of a liquid outer core and a solid inner core. |
| Pangaea | Continents joined together in a single landmass |
| Continental Drift | The continents slowly moving over Earth's surface. |
| Plate Tectonics | Pieces of Earth’s mantle are in constant, slow-motion. |
| Sea-Floor Spreading | The process by which molten material adds new oceanic crust to the ocean floor. |
| Fault | Breaks in Earth’s crust where rocks have slipped past each other. |
| Earthquake | The shaking and trembling that results from the movement of rock beneath Earth's surface. |
| Fault | A break in Earth's crust where slabs of crust slip past each other. |
| Epicenter | The point on the surface directly above the focus. |
| Focus | The point beneath Earth's surface where rock that is under stress breaks, triggering an earthquake |
| Seismograph | A device that records the ground movements caused by seismic waves as they move through the Earth. |
| Magnitude | A measurement of earthquake strength based on seismic waves and movement along faults. |
| Aftershock | An earthquake that occurs after a larger earthquake in the same area. |
| Tsunami | A large wave produced by an earthquake on the ocean floor. |
| Volcano | A weak spot in the crust where molten material comes to the surface. |
| Magma | A molten mixture of rock-forming substances, gases, and water from the mantle. |
| Lava | Magma that has reached the surface. |
| Ring of Fire | A volcanic belt that is formed by the many volcanoes that rim the Pacific Ocean. |
| Hot Spot | An area where magma from deep within the mantle melts through the crust. |
| Crater | The bowl shaped area that forms around a volcano’s vent. |
| Vent | The point where magma leaves a volcano’s pipe. |
| Pipe | A narrow, almost vertical crack in the crust through which magma rises to the surface. |
| Magma Chamber | A large underground pocket of magma. |
| Quiet Eruption | Occur when a volcano’s magma flows easily. |
| Explosive Eruption | Occur when a volcano’s magma is thick and sticky. |
| Pyroclastic Flow | An explosive eruption hurls out ash, cinders, bombs, and gases. |
| Active Volcano | A volcano that is erupting or has shown signs that it may erupt in the near future. |
| Dormant Volcano | A volcano that does not show signs of erupting in the near future. |
| Extinct Volcano | A volcano that is unlikely to erupt again. |
| Hot Spring | Formed by groundwater that has risen to the surface after being heated by a nearby body of magma. |
| Constructive Forces | Shape the surface by building up mountains and landmasses. |
| Destructive Forces | Slowly wear away mountains and other features on the surface |
| Subduction | Process by which the ocean floor sinks beneath a deep ocean trench and back into the mantle. |
| Transform Boundary | A boundary where two plates slip past each other moving in opposite directions |
| Divergent Boundary | The boundary where two plates move apart |
| Convergent Boundary | The boundary where two plates come together |
| Shearing | Stress that pushes a mass of rock in two opposite directions. |
| Tension | Stress that pulls on the crust, stretching rock so that it becomes thinner in the middle. |
| Compression | Stress that squeezes rock until it folds or breaks. |
| Strike-slip Fault | A fault that is created by shearing. |
| Footwall | The half of the fault that lies below the fault. |
| Hanging Wall | The half of the fault that lies above the fault. |
| Normal Fault | The fault is at an angle, so one block of rock lies above the fault while the other block lies below the fault. |
| Reverse Fault | The same structure as a normal fault, but the blocks move in the opposite direction. |
| Fold | Bends in rock that form when compression shortens and thickens part of Earth's crust. |
| Seismic Waves | Carry the energy of an earthquake away from the focus |
| Primary Waves | The first waves to arrive. |
| Secondary Waves | Waves that arrive after P waves. |
| Surface Waves | Waves that move more slowly than P waves and S waves, but they produce the most severe ground movements. |
| Liquefaction | Occurs when an earthquake's violent shaking suddenly turns loose, soft soil into liquid mud. |
