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82 Cards in this Set
- Front
- Back
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how are rocks classified?
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baced on how they are formed then on composition and textur
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what are the 3 groups of rocks?
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Igneous, sedementary, metamorphic
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what are igneous rocks?
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a rock formed from the cooling and solidification of magma or lava
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what are some types of igneous rocks?
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granit, basalt, obisidian, pumice,gabbro, chryalite
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what determines the size of the crytals in ingneous rocks
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the composition o f the magma and the amount of time it takes to cool
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what is the dif. between intrusive and extrusive rocks?
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intrusive in w/in the earths crust where extrusive is outside the earths crust
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what ate metamorphic rocks?
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when other kinds of rocks are changed by heat and pressur in the earth.
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what are some metamorphic rocks?
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marble, quarttzite, schist, slate, qneiss
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what is foliated metomorfic rock?
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alligned in a sheet like formation.
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what is nonfoliated metomorphic rock?
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no particular allignment no particular ordianation
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what determins weither a rock is foliated or not
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weither a rock goes through regonal or contact metamorphism
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what is the dif of regonal and contact metamorphism?
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contact metamorphism is when the rock is in direct contact with magma
regional metamorphism is when not all areas of a very large rock is in contact with magma |
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what textures relate to each contact and regonal metamorphism?
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regonal metamorphism is related to foliation.
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what are sedeimentary rocks?
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rocks that form on the surface of the earth, in the water, or on land. they are composed of differenty sized fragments of other rocks, animal remains, or plant materials.
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what are some types of sedementary rocks?
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sandstone, limestone, shale, and conglomerate.
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how are sedimentary rocks categorized?
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by composition and by the manner which they are formed.
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what are clastic rocks?
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rocks made up of lots of different sized rocks
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what are chemical rocks?
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when water seeps into the rock and gets evaporated and redeposites the minerals it was carrying into the rock
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what aren biologic or ogranic rocks
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from animal or parts of shell remains
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how do the size of the grains in a rock relate to the envirnment it was formed and depositied.
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grain-the energy in the envirnment
shape-natur of transporting mediums a vigirous river can carry larger grains. gental currents can only carry smaller objects. |
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what are the processes that change one kind of rock into another?
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throught heat and pressur any rock can be changed into matamorphic rock.
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list the compositional layers of the earth.
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crust mantle core
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list the structural layers of the earth.
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lithosephere
asthenophere mesosphere outer core inner core |
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where is the earths magnetic feild generated?
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liquid iron in the outter core.
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what causes the magnetic feild around the earth
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motins w/in the core produced electric currents that creat the magnetic feild.
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what ae seismic waves?
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waves of energy caused by the sudden break in rock. they are energy that travels though the earth and is recorded on a seismograph
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what are S waves?
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they arive second, material does not change volume but shears out of shape and snaps back travels only though solids.
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what is a P wave?
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known as primary waves, arive first materials expand and contracts, travels though all materials
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what is the dif. between p and s waves?
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body waves and surface waves body waves can go through the earth inner layers, but surface waves can only travel on the surface of the planet.
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how are seismic waves used tp determine the locations and properties of earths intrerior?
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S waves cannot travel though solids. waves change speeds when introduced into a dif. medium.
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descibe the dif. between oceanic and continental crust
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oceanic-younger, more dense, heaver rocks, basalt
continental-older, less dense, made up of lighter rocks like granite. |
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what is sea-floor speading?
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a prosses by which new ocean floor forms as magma rises to the surface and solidifies, as tectonic plate move away from each other, the seafloor spreads and magma fills in the gap.
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what is the theory of plate tectonics?
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earths crust is made of rigid plates that move the motion of the plates causes continitial drift.
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how do the plate tectonic theory account for features and procedded that occue on or near the Earths surface?
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apart at divergent bounarys=mid ocean ridges
oceanic plates collid with continental plates trenches form as the oceanic plate is subducted 2 continental plates collide mountains form earthquakes and volcanoes occure along most plate boundaries. |
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what is the relationship btween the rock cycle and the plate tectonic theory?
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metamorphic rocks form at convergent where the rocksare put under intense pressure from the colliding plates. as plates diverge, ingeous rocks form as the magma cools. as plates are forced upward, the rocks are exposed to weathering and erosion and can form sedimentary rock
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what is a convergent boundary?
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where plates collide, causing trenches when ocean and contenental plates collide, when two plates of the same dencity collide mountains are formed
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what is divergent bondary?
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where plates move apart, causing mid ocean ridges, and contenental drift.
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what is a transphorm boundary?
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plate slide past eachother.
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what causes the tectonic plates to move?
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convection w/in the mantle/asthenpsphere. warmer rock rises, cooler rock near the surface sinks
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how do rocks bend, fold, and break to create faults?
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when plates move together and put stress on them. land featurs start of as folds and faults.
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what causes earthquakes?
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when plates slide past eachother, collide, or move apart.
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what is the elastic rebound theory?
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how rocks spring back into their oiginal shpar after they have need deformed by seismic forces.
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what is a seiemograph?
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Instuments that recrd the vibrations of the earth quake.
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how are earthquakes measured?
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magnitued is a scale used that meauseres the amp of seismic waves
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what is the epicenter?
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the position on the earths surface directly above the earthquake.
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what is the focus?
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the point at which stress breaks the friction btween 2 plates of the earths crust.
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what is the relationshi[p btween plate tectonics and eartquakes?
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most earthquakes occur along plate boundarys. large earthquakes closer to the surface
deeper- as if one plate is being subducted |
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what inpact do earthquakes have on most humans?
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earthquakes cause buildings and eachother structures to collaps which causes the most injury and death. other dangers include landslides, explotions from broken gas lines, and floods from collapsing dams.
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where would you be most likely to feel a minor earthquake?
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top floors of a tall building
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what is a volcano?
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a vent or a fissure in the earths surface through which magma and gasses are expelled
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what is the difference between lava and magma
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lava is the molten rock or magma that has reached the surface
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where do volcanoes generally occur?
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they generally occur along plate boundaries when plates collide or move apart.
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what are the two different types of volcanic euptions?
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non-explosive or quiet eruptions produces calm lava
explosive eruptions are rare and rapidly erupt ash and rock into the atmosphere |
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what are the different types of lava?
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Aa lava
pahoehoe |
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what is Aa lava
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thin and forms brittle jagged crust and rock int the atmostphere
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what is pahoehoe lava?
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flows slowly and formsa a glassy wrinkled crust.
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what is a shield volcano and how do they form?
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forms from quiet eruptions, thin lava that spreads out over a wide area. sides are not steep.
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what is a cindercone volcano and how do they form?
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formed by moderatly explosive eruptions. made up of pyroclastic material and has very steep sides.
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what is a composite volcano and how do they form?
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form from explosive eruptions follewed by slower flow of lava. forms alternatinf layers of pyroclastic material and lava. also known as a starato volcano.
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what is a hot spot?
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a volcanicly active area forfrom a plate boundary.
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how can not spots be used to determin the motion of tecctonic plates.
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find the dif. in ages and distance and then devide. use direction plates move and how fast they are moving.
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how can volcanoes change the atmostphere, hydrosphere, and other earth systems?
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the lava, gas, and ash that erupt into the atmostphere can remain in the atmostphere and b dispersed around the world by global winds.
the sulfur dioxide combines with water vapor to form sulfuric acid which reflects the sun's energy back into space. this can cause global temps to decrease Also the acid rain has a negative impaxt on vegatation around the world. |
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ow can volcanoes be used to determin plate bounaries?
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composit volcano that usualy form along a striaght line, convergent boundarys where 1 plate subducts.
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what is a fossil and where are most found?
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the remains of physical evidence of an organism preserved by geological processess. most fossils are burried and preserved insedementary rock, but some are trapped in organic matter
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why are fossils important?
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they can provide information about ancient plants, animals, and earth's structure and climate.
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how are fossils grouped?
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1) bones, shells, or other physical remains
2)impression, mold, cast 3)black layer of carbon in the shape of organisms 4)nests, tracke, trails, other evidence left by an animal |
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how is relative dating used in geology?
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by comparing the age of rocks or fossils to other rocks or fossils and estimated order of events can be established.
also known as super position. |
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what is the principle of superposition?
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younger rocks will lie above older rocks if the layers have not been disturbed.
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how can index fossils be used to detemine time sequence?
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index fossils only lived for a short time, when they are found anywhere on our planet the age of the rock layer they are found in can be determined.
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how is a geologic column used in relative dating?
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it shows rock layers in the order in whick they were formed. so when fossiles are found they can be compared to the geologic column and their relative age can be determined.
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what is an unconformity.
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missing rock layers, a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time.
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what is absolute dating?
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any method of measuring the age of an event or object in years, radiometric dating, radiometric decay.
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how are radioactive elements used to date the rocks that contain them?
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all rocks have some radio active material. using a method called radiometeric dating geoligists can estamate the length of time over which decay has been occuring by messuring the amount of radioactive parent element and the amount of stable elements.
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what is a half life?
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the time it takes for half of some radioactive material to decay.
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why can C-14 be used to date a 40,000 year old tree but U-Pb cannot?
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the half life of C-14 is 5730 therefor the specement would have undergone 7 halflives. the half life of U-Pb is 4 bil. so it would be more acurate to messure with C-14 half lives.
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what is a geologic time scale?
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the division of earths history into time units based on the types of life rofms that lived only during that period.
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how is geologic time scale divided?
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Eons are the longest division, Eras are baced on the life forms that were present, periods are sections of an era, eapochs are sections of a period.
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what devides a geologic timescale?
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divitions are blaced on changes in the fossil records.
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Precambrian Period
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4 billion years, 88% of earths life, includes the formation of the earth, formation of life, oxygen rich atmosphere was formed.
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Paleozoic Era.
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the age of the fish, marian life flourished, very few land animals until near the end, largest mass extinction on record ended paleozoic, wiped out *most* invertebrates
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describe te mesozoic era
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age of reptiles, pangea split apart, dinos flourish. 1st memmals appear, mass extinction at the end causes extinction of dinos and other land and sea life.
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describe the Cenozoic Era
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the age of the mammals, the 1st sea mammals apear, humans apear
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