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83 Cards in this Set
- Front
- Back
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What are the four main divisions of geologic time? |
Cenozoic -most recent (lots of mammals), mesozoic (dinosaurs and first flowering plants) , paleozoic (apperance of fish,plants, insects, reptiles, precambrian before shells and hard parts.
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Which one is the oldest? Which are we in now? |
The Precambrian is the oldest, we are in the Cenozoic now.
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What is an Era?
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Era is a period of time marked by distinctive character, events. |
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How do we divide up geologic time (what events or mechanisms are used to separate Eras)?
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We divide up geologic time with large events like mass extinctions/ periods. |
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Be able to draw a diagram showing both the rheological and compositional layers of the earth. Understand the relative sizes and positions of the layers.
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What does rheological or rheology mean? |
is the study of the flow of matter, primarily in a liquid state, but also as 'soft solids' or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force.
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What is the difference between the two naming schemes? |
rheology based on material behaviors (lithosphere, asthenosphere, mantle, and outer and inner core compositional- chemical composition (oceanic and continental crust, mantle, and outer and inner core)
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How do geologists analyze the earth’s interior?
seismic activity, seismic data |
waves travel differently through. seismic energy- measures vibrations throughout the earth
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What are seismic waves?
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are waves of energy that travel through the Earth's layers, and are a result of an earthquake, explosion, or a volcano that gives out low-frequency acoustic energy. Many other natural and anthropogenic sources create low amplitude waves commonly referred to as ambient vibrations.
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What is seismic velocity?
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speed of seismic wave.
A boundary between to different layers is a seismic velocity discontinuity, this represents a change in material properties |
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What can seismic waves and seismic velocities tell us about earth’s interior?
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the waves travel differently through different materials. Wave refracts down in slower material, refacts to shallower angle in faster material. P waves travel through liquid- they bend differently depending what they go through= creates a shadow zone. S waves do not move thru liquid at all
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What layer of the earth do S-waves not penetrate through? Why don’t they make it through this layer? What happens when seismic wave move into a slower or faster material? |
S-Waves can’not travel through liquid.This happens because it is slower than a P-wave
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What rocks are the different compositional layers of the earth similar to? Which of these layers is the least dense?
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Crust is divided into continental, oceanic. Continental crust composition similar to granite. Oceanic crust composition similar to basalt. Mantle peridotite- the upper mantle composed of olivine, lower mantle similar as upper mantle but with minerals that form at very high pressures. Core consists of metallic iron and nickel- iron-nickel alloy
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What is the difference between the Lithosphere and the Crust?
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The lithosphere (litho:rock sphere:layer) is the strong, upper 100 km of the Earth. The lithosphere is the tectonic plate we talk about in plate tectonics. The crust is a chemically distinct layer at the surface of the Earth… Different names for the same area based on different definitions (some difference in depth responding to the different definitions)
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Is the Asthenosphere liquid?
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Relatively weak layer that flows, lower viscosity, NOT A LIQUID (rocks flow)
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What is Isostasy?
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relationship between crustal thickness and elevation, density and thickness and elevation
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What are the two types of isostasy and how are they different?
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airy isostasy and Pratt isostasy- airy: topographic changes accommodated by thickness changes… Pratt: topographic changes accommodated by density differences.
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Why do some layers float higher than others?
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thick blocks higher than thin blocks , dense materials (like more dense wood) are lower. |
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What are the three classifications of rocks?
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metamorphic, igneous, sedimentary
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What makes a rock Sedimentary?
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rocks formed in normal surface environments. Know these** Glaciers carry all sizes and shapes of material, including large boulders, rivers carry silt, sand, cobbles, flat surfaces. Steep mountain fronts have large, angular rocks
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What makes a rock igneous?
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Rocks formed with magma, can erupt ash that falls back to earth and can solidify into rock Lava solidifies to become rock. Volcanoes can erupt ash that falls back to Earth and can solidify into rock.Lava solidifies to become rock. Magma that does not reach Earth’s surface cools and becomes rock. Heat around the magma chamber can bake or otherwise change nearby rocks. Forces deep within Earth can squeeze and transform a rock into a new kind of rock
Distinctive rocks form when hot water cools, either on the surface in hot springs or at depth |
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What is a metamorphic rock?
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What is the theory of plate tectonics?
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The theory that the lithosphere is made up of distinct plates that move around over time.
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What observations led to the theory of Continental drift? What were the flaws with this theory?
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Flaw in the theory- the guy didnt know how it moved… evidence for moving- glaciers, mountain belts, fossils, past climate.
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What is paleomagnetism and how was it used to produce the idea of sea floor spreading?
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is the study of the record of the Earth's magnetic field in rocks, sediment, or archeological materials. Certain minerals in rocks lock-in a record of the direction and intensity of the magnetic field when they form.
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What is the curie temperature, what happens when rocks cool down below the curie temperature?
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The Curie temperature is a point at which materials lose their ferromagnetism, the ability to align their atoms even in the absence of a magnetic field. below curie temp the magnetic metal in rocks hold in place.
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What are the two types of Magnetic polarities? How are these different?
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Normal Polarity, Reversed Polarity. Magnetic field currently flows from south to north (normal polarity) …. flowed from north to south (reverse polarity)
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What happens at mid-ocean ridges when polarities change over time?
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magnetic reversals are recorded by a mid-ocean ridge… Ocean basin pulls apart at mid-ocean ridge and basaltic lava erupts from fissures
As rocks cool, the orientation of Earth’s magnetic field is recorded in rock Reddish colors show normal polarity If magnetic field reverses, rock will acquire a reversed polarity (white bands) With continued plate spreading, a pattern of alternating magnetic stripes is produced |
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What do the locations of earthquakes and volcanoes tell us about plates?
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What kind of boundaries they are, and where they are.
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Where (in a plate boundary sense) would you expect to see earthquakes and volcanoes, and where wouldn’t these things occur?
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Transform wouldnt occur. On convergent boundaries there are shallow earthquakes deeper toward boundary, deep trenches, volcanoes, arcs. Transform no volcanoe, no trench no volcanoes. Divergent new sea floor (distinct), shallow earth quakes , seismic activity.
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What are the forces that drive plate tectonics? Which force is the strongest?
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Subducting down into the earth, oceanic crust gets sucked down other. Slab pull force- responsible for 98% of the force that drives plate tectonics (the strongest). Ridge push 1.8 %. pulled down because of its higher elevation |
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Understand the different types of plate boundaries and the forces that cause them. Know some basic examples of different plate boundaries.
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Transform wouldn’t occur. On convergent boundaries there are shallow earthquakes deeper toward boundary, deep trenches, volcanic, arcs. Transform no volcano, no trench no volcanoes. Divergent new sea floor (distinct), shallow earthquakes , seismic activity |
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What is a mineral? What are the characteristics of a mineral?
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Solid –ice yes, liquid water no!, Natural –not man-made, Inorganic –not shells of a clam, Specific chemical composition –regardless of size Ordered internal structure –glass is not a mineral (amorphous solid) |
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What are some of the tests we use to distinguish minerals and what are these tests trying to distinguish?
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hardness, streak, magnetism, (effervescence- how it dissolves in different type of acid and what is released ) |
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Why do minerals have cleavage?
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Cleavage tells us about the weak planes in the crystal structure |
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What elements make up the most common minerals? Specifically, what makes up silicates? What is a silicate tetrahedron? |
oxygen and silicon make up most of the crust, Silicate tetrahedron: one silicon atom bonded with four oxygen atoms |
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What is the difference between a clastic and a crystalline rock? |
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What is Magma? What is Lava? How are they different?
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Lava above surface, magma below
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What determines if a rock is intrusive or extrusive?
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intrusive below the surface, extrusive above
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Why do rocks melt? Be able to read and use a phase diagram and understand what would happen to a rock if it were heated, cooled, or if the pressure changed.
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Geothermal gradient-interior of earth is hot
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What happens if water is added to hot dry rocks?
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Adding water lowers melting temperature of rocks–makes it easier to melt, harder to crystallize
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How does decompression impact melting?
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Decrease in pressure causes melting
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How do we classify igneous rocks? What are some igneous rock textures? What is the difference between MAFIC and FELSIC rocks? |
Texture= Size, shape, arrangement of mineral crystals |
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Understand the basic classification of igneous rocks (understand differneces between basalt or granite) |
Granite (intrusive): Contains Quartz, Mica, Feldspar |
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Understand the basic classification of igneous rocks (understand differneces between basalt or granite)
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Granite (intrusive): Contains Quartz, Mica, Feldspar
Basalt- extrusive, very dark mafic igneous rock |
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How does cooling rate effect igneous rock texture?
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Slow cooling= large crystals
Fast cooling= small crystals Main texture of igneous rock is determined by cooling rate if it is slow you will add new things. Cool rapidly= glass. some big and little crystals = slow then fast cooling |
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What are the two types of weathering?
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What does thermal expansion, frost wedging, salt/mineral wedging, root wedging, or animal attack do to rocks? What about dissolution, oxidation, or hydrolysis?
Chemical and physical. |
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What happens to sediment during transportation?
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erodes and breaks down. Reduce clast size What are the 4 principles of geology? How can we use them to determine the relative ages of rocks? Be able to do this. Principle of Uniformitarianism Earth processes are basically the same as they were Principle of Original Horizontality Sediments are deposited in flat lying layers Principle of Superposition Younger rocks are deposited on top of older rocks Principle of Cross Cutting Relationships If something cuts through something else it is younger |
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Understand how the energy found in different environments allows specific types of sediments to be accumulated. What size and shape of sediment would you find near mountains? What about in lagoons? Be able to analyze different sedimentary environments and understand what sort of sediments would be deposited in each.
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Making sediment- Chemical weathering- Transportation breaks rock into smaller pieces during transportation clast size is reduced, the farther moved the more round and smaller rocks become |
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What is sorting? What does sorting tell us?
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What happens to sediment to turn it into a rock?
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Compaction of sand grains
Compaction of clay particles Cementation |
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What are some common clastic sedimentary rocks? What sorts of environments do they form in? How do we differentiate between clastic sedimentary rocks?
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Conglomerate, sandstone, breccia, shale
Steepness of slope Strength of current Agent of transport (water, wind, or ice) |
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What are some examples of sedimentary rocks that form by Chemical reactions?
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Rock Salt |
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What about sedimentary rocks that form by organisms?
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Limestone with fossils |
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What is a sea level transgression? Regression? What patterns of rocks do these events cause? Why does sea level change cause different patterns of rock layers?
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Geologists call the advance of sea level and growth of corresponding growth in sedimentary rocks a transgressive sequence When sea level falls we have a regressive sequence Sea moves out, so shoreline retreats toward the sea and beach and lagoon follow Sand that was close to beach now being eroded Beach sand is deposited over lagoon mud: lagoon mud is deposited over reef limestone |
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What is a sedimentary structure? Name a few, how are they different? How are sedimentary structures created?
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A layer of sedimentary rock with a recognizable top and bottom is called a bed. Several beds compose a strata. The overall arrangement of a sequence of beds is called bedding or stratification 3 types of bedding going to deal with- parallel, cross, graded (either big pieces at bottom and small at the top or visa versa) |
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There are two processes that form sedimentary basins. What are they? How do flexural basins form? |
Flexure and Rifting |
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What distinguishes a metamorphic rock from an igneous or sedimentary rock?
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A metamorphic rock is one that has changed from it’s original form (the original rock is called the protolith) into a new one, without becoming a melt or sediment
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Define protolith
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The original rock before metamorphosized
What causes metamorphism? What is metamorphic grade? Metamorphic grade is the level of heat and pressure applied to the rock.Contact metamorphism occurs typically around intrusive igneous rocks as a result of the temperature increase caused by the intrusion of magma into cooler country rock. |
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What is foliation? What are some foliated rocks?
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repetitive layering in metamorphic rocks. Each layer may be as thin as a sheet of paper, or over a meter in thickness.
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What are the different types of metamorphic rocks that shale becomes when metamorphosed? At what metamorphic grades do these rocks form?
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These are the common foliated metamorphic rocks. |
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What happens to sandstone and limestone when they are metamorphosed? What new rocks do they become?
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sandstone becomes quartzite, limestone becomes marble
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What type of coal has the highest metamorphic grade? What are the different types of coal? |
Contact Metamorphism caused by heat transfer from magma body, Regional metamorphism is caused by burial, subduction, heat, and hot fluids |
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What are the intrusive igneous features? What is the difference between a dike and a sill?
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below the surface as intrusive (plutonic), Large crystals Dike is vertical sill is horizontal |
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Where do we find igneous rocks? In what places on the earth do we get melting of rocks?
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Underground, or above ground by magma or lava, Volcanoes or underground magma chambers |
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What is a hotspot?
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hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere.
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What are the different types of volcanoes? How are they different?
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Scoria Cone/ Cinder Cone/ Shield volcano |
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What is the largest type of volcano?
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largest volcanoes are sheild |
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What is tephra?
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tephra is the eruption ash that falls back down |
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What is viscosity? What determines Lava Viscosity? What chemical is responsible for this?
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The viscosity of lava is due to its chemical composition, Low Viscosity lava has low Silica (SiO2) content, This means it has less quartz, High Viscosity lava has high SiO2 content |
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What is a caldera?
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A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption. They are sometimes confused with volcanic craters. |
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What are some volcanic hazards? What is a Lahar? What is a lava flow? What is a lava fountain? What is a pyroclastic flow?
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Hazards obvious. Lahar is a mud flow caused by mixture of pyroclastic material. Pyroclastic flow is some gas and mixed debris, 1000 degrees celsius, move very fast, one of the most dangerous things |
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What sorts of rocks are deposited from composite volcano eruptions?
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What are the intrusive igneous features? What is the difference between a dike and a sill? |
below the surface as intrusive (plutonic), Large crystals Dike is vertical sill is horizontal |
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Where do we find igneous rocks? In what places on the earth do we get melting of rocks?
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Underground, or above ground by magma or lava, Volcanoes or underground magma chambers |
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What is a hotspot?
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hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere.
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What are the different types of volcanoes? How are they different?
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Scoria Cone/ Cinder Cone/ Shield volcano |
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What is the largest type of volcano?
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largest volcanoes are sheild |
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What is tephra?
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tephra is the eruption ash that falls back down |
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What is viscosity? What determines Lava Viscosity? What chemical is responsible for this?
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The viscosity of lava is due to its chemical composition, Low Viscosity lava has low Silica (SiO2) content, This means it has less quartz, High Viscosity lava has high SiO2 content |
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What is a caldera?
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A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption. They are sometimes confused with volcanic craters. |
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What are some volcanic hazards? What is a Lahar? What is a lava flow? What is a lava fountain? What is a pyroclastic flow?
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Hazards obvious. Lahar is a mud flow caused by mixture of pyroclastic material. Pyroclastic flow is some gas and mixed debris, 1000 degrees celsius, move very fast, one of the most dangerous things |
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What sorts of rocks are deposited from composite volcano eruptions?
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