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Glossary
---------------------------------------------------------------------Inner Core: Innermost layer of Earth, densest, hottest, mostly Fe.
Outer Core: Mostly Fe, surrounds inner core, liquid.
Lower Mantle: Thickest layer, ultra heavy rock.
Upper Mantle: Part of lithosphere, brittle.
Crust: You live on it, relatively paper thin, brittle, least dense, floats on mantle.
Lithosphere: Solid part of Earth.
Asthenosphere: Layer of deformable rock below the lithosphere.
Meridian: Line (half circle) on map running from N. pole to S. Pole.
Longitude: Measurement in degrees east or west (of prime meridian).
Hemisphere: One-half of a sphere.
Prime meridian: Half circle line divides east and west.
International Dateline (IDL): Half circle line that marks 24 hours to 0 hours (24
hour day).
Parallel: Line (full circle) on map running from east to west.
Latitude: Measurement in degrees north or south (of equator).
Hemisphere: One-half of a sphere (N-hemi, S-hemi).
Equator: Line that divides N-hemi and S-hemi (longest parallel).
Rheology: The study of the deformation and flow of matter.
Convection: Transfer of heat within a liquid or gas.
Conduction: Transfer of heat through matter by direct contact.
Thermal Radiation: The energy radiated by solids, liquids, and gases in the form of
electromagnetic waves as a result of their temperature.
Deformation: Alteration of shape, as by pressure or stress.
Brittle: Likely to break, snap, or crack, as when subjected to pressure.
Ductile: Easily molded or shaped.
Density: The amount of matter in a given volume.
Viscosity: The extent to which a fluid resists a tendency to flow.
Plate Tectonics: The theory that the Earth’s crust is broken into plates that float on
the upper mantle.
Plate Boundary: Place where two plates meet.
Divergent Boundary: Place where two plates pull apart.
Convergent Boundary: Place where two plates come together.
Transform Boundary: Place where two plates slide past each other.
Oceanic Crust: Dense crust formed by seafloor spreading at Mid-Ocean Ridges.
Continental Crust: Less-dense crust that makes up the continents.
Continental Drift: A theory stating that the Earth's continents have been joined
together and have moved away from each other at different times in the Earth's
history.
Pangaea: Single, giant landmass, or continent, that later broke apart.
Seafloor Spreading: Process that forms new seafloor.
Subduction: Place where crust is forced below other crust.
Mid-Ocean Ridge: An ocean floor feature resembling a mountain ridge on land.
Trench: Deep canyon on the ocean floor formed by subduction.
Hot Spot: A volcanic area that forms as a tectonic plate moves over a point heated
from deep within the Earth's mantle.