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8th Science
Chapter 2 - A Beka Book
| Term | Definition |
|---|---|
| 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
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