#21-MAFICDefinition: Igneous rocks that contain dark colored minerals.

#22-MAGNITUDE Definition: A measure of the size of an

earthquake based on the amount of ground motion experienced: specified on the Richter scale

#23-MANTLE

Definition: the portion of the earth, about 1800 miles thick, between the crust and the core.

#24-METAMORPHISM Definition: The alteration of the texture, composition and minerals of a rock by exposure to heat, pressure or chemical actions.

#25-MINERAL

Definition: A naturally occurring, inorganic solid with a definite composition and ordered internal structure.

#26-MOH’S HARDNESS SCALEDefinition: A comparison scale used during mineral identification.

#27-NORMAL FAULT LINEDefinition: A break in rock caused by tension forces, where rock above the fault surface moves down.

#28-OBLIQUE SLIP FAULT LINEDefinition: A fault that breaks

along a vertical and horizontal angle.

#29-PANGEA Definition: The large, ancient landmass that was composed of all the continents joined together.

#30-PRIMARY SEISMIC WAVEDefinition: Seismic waves that

move rock particles back and forth in the same direction the wave travels.

#31-REVERSE FAULTDefinition: A break in rock caused by compressive forces, where rock above the fault surface moves upward.

#32-ROCK CYCLE Definition: The model that

describes how rocks slowly change from one form to another through time.

#33-Sea Floor SpreadingDefinition: Hess’s theory that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge.

#34-Sedimentary RockDefinition: Rock that forms from

sediments that are compacted and cemented together.

#35-Surface WaveDefinition: A seismic wave that moves rock particles up and down in a backward rolling motion and side to side in a swaying motion.

#36-S-WaveDefinition: A type of seismic wave

in which rock particles vibrate at right angles to the direction of wave travel. Secondary waves cause the rocks they pass through to change in shape.

#37-Transform Fault Definition: A type of strike-slip fault that

accommodates the relative horizontal slip between tectonic plates, and is common along the edges of plates in mid-ocean ridge regions

#38-TsunamiDefinition: A seismic sea wave that begins over an earthquake focus and can be highly destructive when it crashes on shore.

#39-TrenchDefinition: A long, narrow, steep-sided depression in the seafloor formed where one crustal plate sinks beneath another.

#40-VolcanoDefinition: An opening in the

Earth’s surface that erupts sulfurous gases, ash, and lava.