of the trough.

• body wave: Type of seismic wave that travels through the body of a planet; body waves include primary

waves and secondary waves.

• crest: Highest point of a wave.

• Love wave: Surface wave that has a side-to-side motion, much like a slithering snake.

• primary wave (P-wave): Fastest type of body wave, capable of traveling through solids, liquids, and gases.

• Rayleigh wave: Surface wave that has a rolling motion.

• secondary wave (S-wave): Slower moving, transverse body wave that can only travel through solids.

• surface wave: Seismic wave that travels around the ground surface; the two types are Love and Rayleigh

waves.

• trough: Lowest point of a wave.

• wavelength: Horizontal distance between two waves, as measured from crest to crest or trough to trough.

• extinct volcano: Volcano that has not erupted in recorded history and is unlikely to erupt again.
• continental rifting: A divergent plate boundary within a continent causes the continent to thin and break

apart.

• fissure: Crack in the ground that may be the site of a volcanic eruption.
• Mantle Melting: When rock in the mantle melts because of a melting temperature change because of a change in environment.
• Subduction: When an oceanic plate sinks underneath a continental plate