Geology Definitions for Test 1 Prelude- Core: The dense, iron-rich center of Earth. - Crust: The rock that makes up the outermost layer of Earth. - Earth System: The global interconnecting web of physical and biological phenomenainvolving the solid Earth, the hydrosphere, and the atmosphere. - Geologic time scale: A scale that describes the intervals of geological time. - Geologist: The scientist who studies geology. - Geology: The study of the Earth, including our planets composition, behavior and history.- Gravity: The attractive force that one mass exerts on another; the magnitude depends onthe size of the objects and the distance between them. - Hypothesis: An educated guess.- Lithosphere: The relatively rigid, non-flowable, outer 100 -to- 150 km thick layer ofEarth, constituting the crust and the top part of the mantle. - Mantle: The thick layer of rock below the Earth’s crust and above the core. - Plate: One of about 20 distinct places of the relatively ridged lithosphere. - Science: The use of observation, experiment and calculation to explain how natureoperates and scientists are people who study and try to understand natural phenomena. - Scientific Law: Concise statements that completely describe a specific relationship orphenomena. - Scientific Method: A sequence of steps for systematically analyzing problems in a waythat leads to verified results. - Shatter cone: Small, cone-shaped fractures formed by the shock of a meteorite impact. - Theory: A scientific idea supported by an abundance of evidence that has passed manytests and failed none. - Theory of plate tectonics: The theory that the outer layer of the Earth (the lithosphere)consists of separate plates that move with respect to one another. Chapter 1- Accretionary disk: The disk-shaped body of gas, ice and dust onto which matter falls; itultimately evolves into a solar system:- Asteroid: One of the fragments of solid material, left over from planet formation orproduced by a collision of planetesimals, that resides between the orbits of Mars andJupiter. - Asthenosphere: The layer of the mantle that lies 100-150 km and 350km deep; theasthenosphere is relativity soft and can flow when acted on by force.- Atmosphere: A layer of gases that surrounds a planet.- Bathymetry: Variation in depth.- Big Bang theory: A cataclysmic explosion that scientists suggest represents the formationof the universe; before this event, all matter and all energy were packed into onevolumeless point.- Biosphere: the region of the Earth and atmosphere inhabited by life; this region stretchesfrom a few km below the Earth’s surface to a few km above. - Comet: A ball of ice and dust, probably remaining from the formation of the SolarSystem, that orbits the sun. - Cosmology: The study of the overall structure of the Universe. - Crust: The rock that makes up the outermost layer of the Earth. - Cryosphere: The ice components of the Earths system, including glaciers, snow, sea ice,and permafrost. - Crystal: A single, continuous piece of a mineral bounded by flat surfaces that formednaturally as the mineral grew. - Differentiation: A process early in a planets history during which dense iron alloy meltedand dank downward to form the core, leaving less-dense mantle behind. - Dipole: A magnetic field with a north and south pole, like that of a bar magnet.- Earthquake: A vibration caused by the sudden breaking or frictional sliding of rock in theEarth. - Earth materials: Any of the substances (minerals, rocks, metals, sediments, soils)composing the solid Earth. - Earth system: The global interconnecting web of physical and biological phenomenainvolving the solid Earth, the hydrosphere, and the atmosphere.- Ecliptic: The plane defined by a planets orbit. - Erosion: The grinding away and removal of Earth’s surfaces materials by moving water,air, or ice. - Expanding universe theory: The theory that the whole universe must be expandingbecause galaxies in every direction seem to be moving away from us. - External energy: Energy from the sun that drives components of the Earth System; itcontributes to the circulation and flow of the atmosphere and hydrosphere, and serves amajor role in driving erosion. - Galaxy: An immense system of hundreds of billions of stars. - General Circulation Model: A numerical calculation that simulates the flow of theatmosphere and resulting phenomena, due to the changes in the atmospheric temperatureand other parameters.- Geocentric universe concept: An ancient Greek idea suggesting that the Earth satmotionless in the center of the universe while the stars and other plants and the sunorbited around it. - Geosphere: the solid Earth, from the surface to the center. - Geothermal energy: heat and electricity produced by using the internal heat of the Earth.- Geothermal gradient: The rate of change in temperature with depth. - Giant planet: The four outer, or Jovian, planets in the Solar System, which aresignificantly larger than the rest of the planets and consist largely of gas and/or ice. - Groundwater: Water that resides under the surface of the Earth, mostly in pores andcracks of rock and sediment. - Heat: Thermal energy resulting from the movement of molecules.- Heliocentric model: An idea proposed by Greek philosophers around 250 B.C.E.suggesting that all heavenly objects including Earth orbited the Sun. - Hydrosphere: The Earth’s water, including surface water (lakes, rivers, and oceans),groundwater, and liquid water in the atmosphere. - Internal energy: Energy that comes from the Earth’s internal heat; it drives plate tectonicsand therefore, earthquakes, volcanoes, and mountain building. - Lithosphere: The relatively rigid, non-flowable, outer 100 -to- 150 km thick layer ofEarth, constituting the crust and the top part of the mantle.- Magnetic sphere: The region inside the magnetic shield. - Magnetic field: The region affected by the force emanating from a magnet. - Magnetosphere: The region protects from the electrically charged particles of the solarwinds by Earth’s magnetic field. - Melt: Molten liquid rock. - Metal: A solid composed almost entirely of atoms of metallic elements, it is generallyopaque, shiny, smooth, malleable, and come conduct electricity. -