| A | B |
|---|
| geologists | scientists who study forces that shape Earth |
| constructive forces | build up mountains and landmasses |
| destructive forces | wear away mountains and other features on Earth |
| crust | layer of rock that forms Earth's outer skin |
| mantle | layer of hot rock below crust |
| lithosphere | rigid layer of uppermost mantle and lower crust |
| asthenosphere | soft layer of mantle, convection currents here move the plates |
| outer core | layer of molten metal around inner core |
| inner core | dense ball of solid iron and nickel that spins, causing Earth's magnetic field |
| radiation | transfer of heat by electromagnetic waves |
| conduction | heat transfer by direct contact with particles of matter |
| convection | heat transfer because of movement of heated fluids |
| Alfred Wegener | developed the idea of continental drift |
| Pangaea | super continent, one land |
| continental drift | theory that says the continents are slowly moving over Earth's surface |
| Evidence supporting Wegener's theory | evidence from landforms, from fossils, and from climate |
| Why scientists rejected Wegener's theory | He could not explain the cause of the movement of the continents |
| mid-ocean ridge | longest mountain chain, continuous |
| sea-floor spreading | the process occurring at mid ocean ridges that adds new material to the ocean floor |
| subduction | process by which the ocean floor sinks beneath continental crust, forming a deep-ocean trench |
| plates | large sections of the lithosphere that are moved by convection currents |
| plate tectonics | geological theory that states pieces of Earth's lithosphere are in constant slow motion |
| fault | a deformation of the Earth's crust that results in a break |
| transform boundary | place where two plates slip past each other |
| divergent boundary | place where two plates move apart |
| convergent boundary | place where two plates come together or collide |
| land subsidence | occurs when land sinks because of geologic process or human activities |
| fold | crustal deformation caused by compression that results in folded layers of rock |
| syncline | a downward fold of rock |
| anticline | an upward fold of rock |
| Rift Valley | Formed by extensional stress |
| Island arcs | formed by the subduction of oceanic crust below oceanic crust |
| fault block mountains | formed by land between two faults cause by extensional stresses |
