| A | B |
|---|
| abyssal plain | A broad relitively flat region of the ocean that lies at least 4.5km below sea level. |
| apparent polar-wander path | A path on the globe which a magmetic pole appears to have wanderd over time; in fac the continents drift, while the pole stays fairley fixed |
| asthenosphere | The Layer of the mantle that lies between 100-15 km and 350 km deep; the asthenosphere is relatively soft and can flow when acted by force |
| Collision | The process of two bouyent pieces of lithosphere converging and squashing together. |
| Contintal drift | The idea that continents have moved and are still moving slowly across the Earth's surface. |
| Contintal rift | A linear belt along which contintal lithosphere stretches and pulls apart |
| Convergent boundry | A boundry at which two plates move toward each other so that one plate sinks beneth the other |
| Core | the dense iron rich part of the Earth |
| crust | The rock that makes up the outermost layer of the Earth. |
| mantle | The thick layer of rock below the Earth’s crust and above the core |
| earthquake | A vibration caused by the sudden breaking or frictional sliding of rock in the Earth. |
| geothermal gradient | The rate of change in temperature with depth. |
| Moho | The seismic-velocity discontinuity that defines the boundary between the Earth’s crust and mantle |
| lithosphere | The relatively rigid, nonflowable, outer 100- to 150-km-thick layer of the Earth, constituting the crust and the top part of the mantle. |
| rock | A coherent, naturally occurring solid, consisting of an aggregate of minerals or a mass of glass |
| mineral | A homogenous, naturally occurring, solid inorganic substance with a definable chemical composition and an internal structure characterized by an orderly arrangement of atoms, ions, or molecules in a lattice. Most minerals are inorganic. |
| magnetic field | The region affected by the force emanating from a magnet. |
| Pangaea | A supercontinent that assembled at the end of the Paleozoic Era. |
| sea-floor spreading | The gradual widening of an ocean basin as new oceanic crust forms at a mid-ocean ridge axis and then moves away from the axis. sea ice Ice formed by the freezing of the surface of the sea. |
| subduction | The process by which one oceanic plate bends and sinks down into the asthenosphere beneath another plate. |
| plate tectonics | The theory that the outer layer of the Earth (the lithosphere) consists of separate plates that move with respect to one another. |
| magnetic dipole | An imaginary vector that points from the north magnetic pole to the south magnetic pole of a magnetic field. |
| magnetic poles | The ends of a magnetic dipole; all magnetic dipoles have a north pole and a south pole |
| paleomagnetism | The record of ancient magnetism preserved in rock. |
| mid-ocean ridge | A 2-km-high submarine mountain belt that forms along a divergent oceanic plate boundary. |
| trench | A deep, elongate trough bordering a volcanic arc; a trench defines the trace of a convergent plate boundary. |
| volcanic arc | A curving chain of active volcanoes formed adjacent to a convergent plate boundary. |
| magnetic anomaly | The difference between the expected strength of the Earth’s magnetic field at a certain location and the actual measured strength of the field at that location. |
| magnetic reversals | The change of the Earth’s magnetic polarity; when a reversal occurs, the field flips from normal to reversed polarity, or vice versa. |
| plate boundaries | The border between two adjacent litho sphere plates. |
| divergent boundary | A boundary at which two lithosphere plates move apart from each other; they are marked by mid-ocean ridges. |
| transform boundary | A boundary at which one litho sphere plate slips laterally past another. |
| hot spots | A location at the base of the lithosphere, at the top of a mantle plume, where temperatures can cause melting. |
| plate velocity | The movement of one litho sphere plate with respect to another. |
| terrestrial planets | Planets that are of comparable size and character to the Earth and consist of a metallic core surrounded by a rock mantle. |
| differentiation | a process early in a planets history during which dense iron alloy melted and sank downward to form the core |
| dwarf planet | a smaller planet like pluto |
| epicycles | was a geometric model used to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets. |
| hydrosphere | the earhts water including surface water, groundwater and liquid water in the atmosphere |
| isostasy | the condition that exists when the bouyency force pshing the lithosphere u equals the gravititational force pulling lithosphere down. |
| jovian planets | a term used to describe gas giants like jupiter |
| lithosphere plates | one of many distinct pieces of the lithosphere that are seperated from one another |
| mafic | a tem in refrence to magmas or igneous rocks that are relitivley poor in silica and rich iniron and magnesium. |
| Marine magnetic anomaly | the difference between the expected strength of the earths main dipole field at a certain location on the sea floor and the actual measured strength of the magnetic field at that location |
| Planet | an object that orbits a star, is roughly spherical, and has cleared its neighborhood of other objects |
| plate tectonics | the theroy that the outter layer of the earth consists of seperate plates that move with respecct to one another |
| pressure | force per unit capita or the push acting on a material is the same in all directions |
| silicate | minerals built from silicon-oxygen tetrahedra |
| silicic | rich in silicawith reltivly little iron and magnesium |
