| A | B |
|---|
| ocean-floor spreading | the formation of new oceanic crust at mid-ocean ridges |
| subduction | the process by which sections of crust collide, causing the more dense crust to sink down below the less dense crust |
| mid-ocean ridge | underwater mountain range located between 2 continents; where ocean floor spreading takes place |
| trench | a deep valley on the ocean floor; shere subduction occurs |
| fault zone | a section of the Earth's crust containing faults thousands of kilometers long and hundreds of kilometers high |
| oceanic crust | the portion of the Earths crust beneath the ocean |
| continental crust | the portion of the Earth's crust that makes up the land masses |
| isostasy | the balance or equilibrium between the downward force of the Earth's crust and the upward force of the mantle |
| prime meridian | longitude of zero degrees; runs through Greenwich, England |
| latitude | measures in degrees north and south of the equator; horizontal parallel lines; 0-90 degrees |
| equator | the imaginary line that circles the globe; located halfway between the north and south poles |
| Richter Scale | the numerical measure of the magnitude of an earthquake; it ranges from one to ten; the larger the number, the greater the magnitude |
| seismograph | an instrument that detects the movement of the earth during an earthquake and records it |
| tracing | the squiggly line that is the record of movement of the drum |
| magnitude | the amount of energy released at the focus of an earthquake |
| seismic wave | vibrations that radiate outward from the focus of an earthquate; they are caused by the movement of rock. It can be felt and observed |
| shear waves | cause rock particles to jigle up and down at right angles to the wave |
| focus | the point inside the earth's crust at which the earthquake originates |
| compressional wave | cause particles of rock to bump into each other |
| epicenter | the poin directly above the focus on the surface of the earth |
| earthquake | a great movement of the ground due to a sudden release of stored energy along a fault in the earth's curst |
| stress | a response to pressure; the effect of high heat or pressure on rocks |
| fault block | a section of crust between two faults |
| compression | pressure exerted tward the center from opposite sides |
| fault | a crack in the earth's crust along which movement occurs |
| dome | a type of mountain formed when a pocket of magma pushes against the layer of crust above it |
| theory | an idea that explains many observations about the natural world and predicts other observations |
| mineral | a naturally occuring solid element or compound with many specific chemical and physical properties |
| law | a descriptive generalization about how some aspect of natural world behaves under stated circumstances |
| metamorphic rock | rock that forms deep within the earth when existing rocks are subjected to tremendous heat and pressure |
| crystal | a solid whos atoms are lined up in organized, repeating patterns |
| rock cycle | a cycle describing all the ways in which rocks can change from one type to another |
| fact | an observation that has been repeatedly confirmed |
| weathering | the process where rocks in the earth's crust are broken donw |
| International Date Line | an imaginary vertical line running from the north to the south poles; directly opposite the Prime Meridian |
| Ring of Fire | describes the pattern of earthquakes and volcanoes that are located all around the edge of the Pacific Ocean |
| longitude | measured distances east and west from an imaginary verticl line called the prime Meridian; 0-180 degrees |
| convection current | a circular current created when a portion of a substance is heated and rises, while cooler portions sink |
