Comprehensive 8th Grade Earth Science and Seismology Study Notes

Geology: The scientific study of the earth.
Crust: The earth's outer layer of solid rock.
- Oxygen: The most abundant element in the earth's crust.
- Moho (Mohorovičić Discontinuity): The lower boundary of the earth's crust.
Sediments: Deposits of sand, mineral fragments, or organic materials usually left by wind or water.
Mantle: The middle layer of the earth.
- Asthenosphere: Plastic rock located in the lower portion of the upper mantle.
- Transition Zone: The portion of the mantle located between $400\,\text{km}$ and $1050\,\text{km}$ beneath the surface.
- Core-Mantle Boundary: The portion of the earth that makes up the bottom of the mantle.
Core: The central part of a planet.
- Inner Core: The innermost part of the earth, said to be solid iron or nickel.

Volcanic Mountain: A mountain that formed when molten rock erupts from a hole in the earth's crust.
Folded Mountain: A mountain believed to have formed when the edges of two tectonic plates were pushed together.
Domed Mountain: Formed when molten rock is forced beneath an overlaying rock layer.
Anticline: An arch-like structure formed when rocks buckle upward during folding.

Fault: A fracture zone formed when a layer of rocks breaks and moves due to the strain of forces upon it.
Thrust Fault: A fault that results when rocks on one side of the fault are shoved on top of the rocks on the other side.
Tectonic Earthquake: A sudden movement of rock beneath the earth's surface.
Catastrophic Plate Tectonics: A Creationist model in which the earth's crust broke into tectonic plates at the beginning of the flood.
Elastic Rebound Theory (Elastic Rebound): A theory stating that rocks on either side of a fault spring back to a position of little or no strain at the moment of an earthquake.

Seismology: The scientific study of earthquakes.
Hypocenter: The underground point at which an earthquake begins.
Epicenter: The point on the earth's surface directly above an earthquake's hypocenter.
Shallow-Focus Earthquakes: Account for about $85\%$ of all earthquakes and originate at depths of less than $20\,\text{km}$ .
Primary (P) Waves: A type of earthquake wave that consists of a rhythmic push-pull motion in the direction of wave travel.
Aftershock: Any of the smaller earthquakes or tremors that often follow an earthquake.
Global Earthquake Belts:
- Circum-Pacific Belt: The most active earthquake zone, which borders the Pacific Ocean.
- Alpide Belt: An earthquake zone that stretches from the mountains of northern Africa through parts of Europe.

Seismometer: A device that detects the earth's movements.
Seismograph: An instrument used to record and study earthquake waves. Scientists use a seismograph to determine the exact point where an earthquake begins.
Moment Magnitude Scale: An earthquake magnitude scale based on measuring the size of the earthquake's source.
Modified Mercalli Scale: A scale used to describe and evaluate the effects of an earthquake on man.
Geographic Information System (GIS): A computer system that stores and processes geographic data.
Topographic Map Review: Includes map examples located on pages $36$ and $37$ for test review.

Ring of Fire: A narrow zone of active volcanoes that parallels the Circum-Pacific earthquake belt.
Pyroclast: A particle or block of solid volcanic ejecta.
Volcanic Explosivity Index (VEI): A scale used to measure the explosiveness of a volcano's eruption (covered across pages $51$ through $65$ ).