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8th Science

Chapter 2 - A Beka Book

Geology The study of the earth
Geologists Scientist who study the earth
The great Flood in Genesis 7 and 8 are undoubtedly responsible for what? Most of the earth's present features and fossils
What are the earth's three major layers based on composition? The crust, mantle, and core
Sediments Deposits of sand, mineral fragments, or organic matterials; usually left by wind or water
The most abundant element in the earth's crust Oxygen
Silica A compound found in sand
The crust's composition varies depending on what? Whether the crust underlies the continents or the ocean
Crust The earth's outer layer made of solid rock
Seismic waves Earthquake vibrations; derives everything we know about beneath the crust
Mantle The earth's middle layer
Mohorovicic discontinuity (aka. Moho) The part of the earth where the density of the rocks change; the place between the crust and mantle
Upper mantle Extends from the Moho down about 250 miles
Lower mantle Extends from about 650 miles to about 1800 beneath the surface
The area in between the upper and lower mantle Transition zone
Rocks that flow like a thick, syrupy liquid in slow motion Plastic rock
The deeper you go in the earth, the ___ ___ ___ ___. higher the temperature becomes
Core-mantle boundary (aka. The Gutenberg Discontinuity) Lies approximately 1800 beneath the surface and marks the bottom of the mantle
Core the central part of the earth
Outer core made of liquid
Inner core Solid
Plates "float" like rafts on the plastic rock of the upper mantle
Lithosphere "sphere of stone" A region of the earth's crust and upper mantle; composed by the eight large plates and several smaller plates
Plate tectonics The theory that the earth is composed of plates
Some advocates believe that at on time all the continents were connected together into one huge land mass called ___. Pangaea
Forces The pulling or pushing of one object upon another
When a layer of rock breaks and moves due to the strain of the forces upon it, the fracture zone is called a(n) ___. fault
Normal fault Occurs when rocks along one side of a fault sink vertically; forms cliffs
Strike-slip fault Occurs when rocks along one side of a fault move horizontally along the fault
Thrust fault Results when rocks on one side of a fault are shoved on top of the rocks on the other side
Fold Forms by the bending or buckling of rocks under great force
Syncline Rocks that bend downward during the folding process form this trough-like sturcture
Rocks that buckle upward during folding form and arch-like structure called a(n) ___. anticline
Mountains Elevated land masses that are higher than hills
Domed mountains Form when molten rock is forced beneath an overlying rock layer
Volcanic mountains Form when molten rock erupts form a hole in the earth's crust
Folded mountains Form when the edges of two adjacent rock layers were pushed together, causing the layers to buckle like a wrinkled rug
Fault-block mountains Form along a fault; the rocks on one side are forced upward, while the other rocks sink
Topographical map Show an area's elevation and natural features as well as man-made structures
Contour lines The curving or circular lines that show the terrain's shape and elevation
Tectonic earthquakes Earthquakes that result form sudden movements of rock beneath the earth's surface
Tremor A weak earthquake
Tsunamis Giant sea waves
Even the largest earthquakes typically last a(n) ___. minute
Aftershocks Smaller earthquakes or tremors that often follow and earthquake
Seismology The study of earthquakes
Seismologist Scientist who study earthquakes
Tectonic earthquakes are primarily the result of ___. faulting
Faulting The sudden movement of rock masses along a fault
Elastic rebound theory The theory that rocks on either side of a fault spring back to a position of little or no strain at the moment of an earthquake, triggering vibrations in the earth's crust
Fault scarp A short cliff made when rocks along one side of the fault may be lifted several feet higher than those on a cliff
San Andreas fault A strike-slip fault that moves about 2 inches a year
Slikensides Rocks along a fault may be polished smooth by the motion of the horizontal pressures that slide rocks n opposite directions
Friction The resistance caused by moving one object against another
Focus The point at which and earthquakes begins
Epicenter The point on the earth's surface directly above the focus
Shallow focus earthquakes make up 85% of earthquakes; originate at depths less that 44 miles below the surface
Intermediate focus earthquakes 12%; occur from depths of 44-186 miles
Deep focus earthquakes 3%; originate at depths more than 186 miles
Name the 3 earthquake waves P, S, and surface waves
P waves (primary waves) travel the fastest; consist of a rhythmic push-pull motion in the direction of wave travel
S waves Travel the second fastest; consist of a rhythmic side-to-side motion that occurs at right angle to the direction of wave travel
Surface wave Travel the slowest;P and S waves together generate this third wave when they reach the earth's surface; the waves are like ocean waves
Seismograph An instrument used to record and study the vibrations caused by earthquakes
Seismogram A record produced by the seismogram
Apide belt 15% of all earthquakes occur on this zone
The most important thing to do during an earthquake Not panic
Foreshocks Smaller earthquakes that occur before the main earthquake
Modified Mercalli Scale (MM scale) Describes and evaluates the effects of an earthquake on man
The MM scale is not a mathematical measurement of what? An earthquakes strength or size
Richter Magnitude Scale measures an earth quake's strength
The moment magnitude scale The most reliable method for measuring an earthquake magnitude
Earthquake waves are helpful why? They tell us more of the earth's interior
San Andreas Fault Observatory at Depth (SAFOD) A program who's mission is to better understand earthquakes
It is presently "impossible" to predict ___ ___ __ ___ ___ ___. exactly when an earthquake will occur
Fixed base systems Buildings constructed on bedrock
Base isolated systems Buildings that rest on isolaters that absorb the seismic energy
Energy dissipating devices are added to structures to absorb additional seismic energy
Volcano an opening in the earth's surface through which hos gases, ash, and molten rock are ejected from the earth's interior
Vent The channel through which the gases and ash and rock are ejected
Magma molten rock
Magma chamber the reservoir of magma
Cone a conical mountain created when solid materials ejected from a volcano accumulate
The underground ___ ___ is the actual source of the eruption. magma chamber
Volcanology the study of volcanoes and volcano related phenomena
Volcanologist scientists who study volcanology
Cinders volcanic ash and rock fragments
Cinder cone volcanoes Volcanoes that consist primarily of cinders
Shield volcano Volcanoes that pour large quantities of highly fluid lava in rather mild eruptions form this broad, gently sloping volcano
Composite volcanoes (stratovolcanoes) Produce both cinder and lava; symmetrical and wide based
Active volcano A volcano that has erupted within recorded history or is currently producing seismic activity
An inactive volcano that could erupt again Dormant volcano
Extinct volcano A volcano that will probably not erupt
Ring of fire a belt on which over half of the world's active volcanoes are
What two factors determine the violence of a volcano's eruption? The viscosity of the magma and the amount of dissolved gas contained in the magma
Viscosity "syrupiness"
Ejecta any substance emitted by a volcano
lava molten rock that flows from a volcano
Pohoehoe lava "ropy" lava; this lava hardened surface looks like ropes
aa lava "blocky" lava
Lava that solidifies almost instantly and forms rounded structures pillow lava; the lave resembles a pillow
Pyroclasts particles or blocks of solid volcanic ejecta
Volcanic ash tiny droplets of lava that are light enough to be carried by the wind
Larger than volcanic ash but less than 64 millimeter in diameter Lapilli
Volcanic blocks Solid, irregularly shaped lumps of hardened lava; usually large and bolder-like
Volcanic bombs form when lava is thrown high into the air in a liquid or semiliquid state and hardens into rock before it hits the ground
A volcano's most dangerous feature is the fierce blast of ___ and super heated ___ that accompanies some volcanic eruptions. ash, gases
Pyroclastic flow consists of a super-heated cloud of gas and volcanic ash that travels swiftly down the volcano slope as an avalanche
Huge bowl-shaped craters Calderas
Lava tunnels (or lava tubes) Form when the surface of a large lava flow hardens but the lava beneath remains molten
When magma is forced through cracks and weak spots in the rocks surrounding the magma chamber and solidify, producing masses of volcanic rock just beneath the surface called ___ ___. Igneous intrustions
formed when volcanic magma hardens in a vertical crock or fissure Dike
Formed when magma squeezes between two horizontal layers of rock sill
A dome like intrusion laccolith
Far larger that laccoliths Batholiths
Created by: nelsonclan