Vocabulary - Volcanoes, Earthquakes, Plate Tectonics, and Fossils
Terms
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- surface waves
- waves of energy that reach Earth's surface during an earthquake, travel outward from the epicenter, and move rock particles up and down, and side to side
- batholith
- largest intrusive igneous rock bodies that form when magma cools underground before reaching Earth's surface
- seismograph
- device used by seimologists to record primary, secondary, suface waves from earthquakes
- magnitude
- measure of the energy released by an earthquake
- sill
- intrusive igneous rock body formed when magma is squeezed into a horizontal crack that cuts across rock layers and hardens
- convection current
- cycle of heating, rising, cooling, and sinking that is thought to be the force behind plate tectioncs
- outer core
- liquid core that surrounds Earth's solid inner core, and that is made mostly of iron
- index fossil
- fossil of a species that existed on Earth for only a short time, were abundant, and were widespread geographically
- pertified remains
- fossils that form when some or all of the original materials that made up the organisms are replaced with minerals
- principle of superposition
- states that for undisturbed layers of rock, older rocks lie underneath younger and younger rocks
- focus
- in an earthquake, the point beneath Earth's surface where energy release occurs
- uniformitarianism
- states that Earth processes happening today are similar to those that happened in the past
- fault
- surface along which rocks break and move
- unconformity
- gaps in the rock layers due to erosion, nondeposition, or both
- plate
- surface along which rocks break and move
- caldera
- large opening formed when the top of a volcano collapes
- crater
- steep-walled depression around a volcano's vent
- fossils
- remains or traces of a once living organism reserved by rock
- tsunami
- powerful seismic sea wave that can travel thousands of kilometers in all directions and that begins over an earthquake focus
- earthquake
- vibrations caused by breaking rocks along faults
- athenosphere
- plastic-like layer below the lithosphere
- continental drift
- hypothesis proposed by Alfred Wegener that the states that continents have moved slowly to their current locations on Earth
- carbonaceous film
- fossil formed when the remains of a once living organism are subjected to heat and pressure, leaving only a thin film of carbon behind
- secondary waves
- waves that travel outward from an earthquke's focus and move through Earth by causing particles in rocks to vibrate at right angles to the direction of the wave
- tephra
- bits of rock or solified lava dropped from the air
- primary waves
- waves that travel outward from an Earthquake's focus and cause particles in rocks to move back and forth in the same direction the wave is moving
- lithosphere
- rigid, outermost layer of Earth that is about 100km thick, and is composed of the crust and part of the upper mantle
- inner core
- very dense, solid center od the Earth that is made of mostly iron with smaller amounts of oxygen, silicon, sulfur, or nickel
- mantle
- largest layer inside Earth, lying directly above the outer core and that is made mostly of silicon, oxygen, magnesium, and iron
- mold
- fossil formed when an organism is buried, decays, and leaves behind a hollow place in rock
- normal fault
- break in rock due to tension forces, where rock above the fault surface moves downward in relation to rock below the fault surface
- radioactive dating
- process to determine the absolute ages of rocks by measuring the amounts of parent and daughter materials in a rock
- volcano
- opening in Earth's surface that often forms a mountain when layers of lava and volcanic ash erupt and build up
- hot spot
- location in the mantle that is hotter than any other areas and that melts rock, which is forced up toward the crust as magma
- relative dating
- method to determine the order of events and relative age of rocks by examining the position of rocks in a sequence
- cinder cone volcano
- steep-sided volcano made of loosely packed tephra
- seismologist
- scientist who studiesearthquakes and seismic waves
- half-life
- time needed for one half-life the mass of a sample of a radioactive isotope to decay
- dike
- intrusive igneous rock body formed when magma is squeezed into a vertical crack that cuts across rock layers and hardens
- reverse fault
- break in rock due to compression forces, where rocks above the fault surface move upward and over the rocks below the fault surface
- composite volcano
- a volacano formed by alternating layers of tephra and lava and that is found mostly where Earth's plates come together
- seismic waves
- energy waves that are produced at and travel outward from the earthquake's focus
- seafloor spreading
- theory that magma from below Earth's crust is forced upward toward the surface at a mid-ocean ridge, flows from the cracks as the seafloor spreads apart and bcomes solid as it cools, forming new seafloor
- crust
- Earth's outermost layer, which varies in thickness from about 5km to 60km and is separated from the mantle by the Moho Discontinuity
- plate tectonics
- theory that Earth's crust and upper mantle are broken into sections that move around on a plastic-like layer of the mantle
- strike-slip fault
- break in rock due to shearing forces, where rocks on either side of the fault suface move past each other with little upward or downward movement
- cast
- fossil formed when sediments fill in a mold and harden into rock
- vent
- an opening on Earth's surface where magma is forced up and flows out as lava
- pangaea
- single large landmass made up of all the continents connected together that broke apart 200 million years ago
- shield volcano
- a broad volcano with gently sloping sides
- epicenter
- point of Earth's surface directely above an earthquake's focus
- volcanic neck
- solid, igneous core of a volcano left behind when a volacno stops erupting
- absolute dating
- process that uses the properties of atoms in rocks and other objects to determine their exact ages, in years
- radioactive decay
- release of nuclear particles and energy from unstable atomic nuclei