GEOL Exam 2
During the earthquake cracks appeared with water seeping up through them- this is called
Liquefaction
When the earthquake struck, the seismic waves that Japan's automatic warning systems first detected were
P waves
23. Know the different types of seismic waves generated in an earthquake
P-waves (P stands for primary) are compressional body waves. FASTEST S-waves (S stands for secondary) are shear body waves. NEXT FAST L-waves (L stands for Love) are surface waves that cause the ground to shimmy back and forth. SLOWEST R-waves (R stands for Rayleigh) are surface waves that cause the ground to undulate up and down. SLOWEST
42. When did the supercontinent Pangaea form and during what Period did it start to break apart?
Pangaea, the supercontinent formed at the end of the Paleozoic, lasted for about 100 million years. Then during the Triassic and Early Jurassic Periods, rifting commenced and the supercontinent began to break up.
40. When and what was the Permian Extinction? The Great Cambrian Diversification?
Permian Extinction: 299-252 ma Ended with major extinction >80% of marine species went extinct, among others - why? Pangaea? Meteorite? Magmatism? Ocean acidification? Ocean anoxia? Great Cambrian Diversification Faunal diversity increased in the early cambrian Referred to as the "great cambrian biodiversification" Rapid diversification Mollusks, brachiopods, nautiloids, etc Possible external causes Preservation Global warming Supercontinent breakup Faunal diversity explode in early cambrian
41. During what Eon and Era did complex organisms (plants and animals) evolve to live on terrestrial (land) habitats?
Phanerozoic Eon Middle Paleozoic Era (devonian period)
5. What is photosynthesis? What is the chemical reaction that describes it?
Process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a byproduct. Co2+h2o = ch2o+o2
38. What are prokaryotes and eukaryotes, and during which Eons did they evolve?
Prokaryotes- their cells do not contain a nucleus, a distinct envelope containing the cell's DNA (Archean eon) Eukaryotic- organisms whose cells contain a nucleus (Proterozoic Eon)
37. When did the oxygen levels in Earth's atmosphere rise rapidly?
Proterozoic Eon
33. How does numerical geochronology work? What kind of rocks do we usually date using these techniques?
The 1896 discovery of radioactivity, the spontaneous emission of energy by certain atoms, provided the key to determine numerical ages. By the 1950s, researchers had developed techniques to measure changes that radioactive atoms undergo when they produce energy, and therefore, to calculate numerical ages of rocks. Geologists now refer to such techniques as isotopic dating (or radiometric dating), and to studies that involve the determination and interpretation of numerical ages as geochronology. Primarily igneous rocks Occasionally metamorphic rocks Rarely sedimentary rocks
Why did Miyako's 30-foot high sea wall fail to protect the town from the tsunami
The earthquake caused the coastline to drop feet, lowering the walls
46. What major tectonic events took place during the Cenozoic Era?
The final stages of Pangaea's breakup separated Australia from Antarctica and Greenland from North America. The Atlantic Ocean continued to grow because of seafloor spreading on the Mid-Atlantic Ridge, so the Americas have moved progressively away from Europe and Africa.
What were the major events that happened on Earth during the Hadean Eon? What was the Earth's atmosphere composed of during this time?
The first eon, the hadean eon, is aptly named 4.56 to 4.0 Ga (billion years) ago January 1 to February 13 in our Year of earth history Earth differentiated (core, mantle, primitive crust) Partially to completely molten during this process The moon formed during the hadean eon Likely by a giant impact Was a time of major impacts Primitive basaltic crust Lunar record Hadean eon: earth's earliest atmosphere 4.56 to 4.0 Ga (billion years) ago January 1 to february 13 in our year of earth history Primitive atmosphere Derived from "outgassing" volcanoes Consisted of N2, NH3, CH4, H2O, CO, CO2, SOx Hadean eon: earth's earliest hydrosphere Evidence for earliest ocean, once cool enough to condense Possible early life... But the record has been wiped out
30. What are fossils and in what kind of rocks do we find them?
The remnant, or trace, of an ancient living organism that has been preserved in rock or sediment. Sedimentary rocks
The height and intensity of the tranmi varied dramatically because of the
Varying depth of the seabed Shape of the coastline (cliffs, bays, inlets) Topography of the land (low lying vs hilly)
THE FOLLOWING STATEMENT IS FALSE: The explosions at the Fukushima nuclear power plant were
caused by the buildup of uranium gas.
THE FOLLOWING STATEMENT IS TRUE: THe earthquake in Japan created a tsunami that caused
damage thousands of miles away in the Hawaiian Islands, and killed a person in california who went to the beach to take photos of the tsunami
THE FOLLOWING STATEMENT IS TRUE: The pacific Northwest of the US (Vancouver Island to Northern California)
is a zone of high tsunami risk because of the potential of a major earthquake in the region.
34. What is radioactive decay? What does "half-life" mean?
they have different atomic masses, are called isotopes of the element some isotopes of an element are stable, in that atoms of the isotope last forever without change. Other isotopes are unstable, in that they eventually undergo radioactive decay, or nuclear decay, a process that releases energy stored in nuclear bonds in the nucleus. Some types of radioactive decay result in the expulsion of fragments (known as alpha particles and beta particles) from the nucleus of an atom. When this happens, the atom's atomic number changes, and as a result, the atom becomes a different element. Physicists refer to an isotope that can undergo radioactive decay as a radioactive isotope. An atom of a radioactive isotope that has not yet decayed is a parent atom, whereas the product of radioactive decay is a daughter atom. They can measure how long it takes for half of a group of parent atoms to decay. This time is called the half-life.
What are the major categories of sedimentary rocks?
Clastic sedimentary rocks: formed from cemented together clasts (solid fragments and grains broken off of pre-existing rocks) Biochemical sedimentary rocks: consist of shells- Numerous organisms have evolved the ability to extract dissolved ions from seawater to make solid shells. When the organisms die, the solid material in their shells survives. When this material is lithified it comprises the biochemical sedimentary rock. Organic sedimentary rock: consists of carbon rich relics of plants or other organisms. Organic debris (guts of organisms) that settles along with other sediment is eventually buried. When lithified, organic-rich sediment becomes organic sedimentary rock. Chemical sedimentary rock: is made of minerals that precipitated directly from water solutions - rock formed primarily by the precipitation of minerals from water solutions
2. What are some of the most common clastic sedimentary rock types? Chemical sedimentary rock types?
Clastic: Sandstone- consists of quartz sand grains cemented together--- other examples: breccia, conglomerate, sandstone, siltstone, and shale. Chemical: Evaporites (products of saltwater evaporation), Travertine (Chemical Limestone (composed of crystalline calcium carbonate (CaCO3) that precipitates directly from groundwater), Colostoen (Contains mineral dolomite (CaMg(CO3)2) - equal amounts of calcium and magnesium - Forms by chemical reaction between solid calcite and magnesium-bearing groundwater), Chemically precipitated chert (Petrified wood is chert that forms when silica-rich sediment such as ash from a volcanic eruption buries trees)
15. What are the different types of geologic stress that can lead to deformation?
Compression: When a rock is squeezed together Tension: when rock is pulled a part Shear stress: when one part of a rock body moves sideways past another Pressure: same amount of compression on all sides of an object Matters whether it is in the E-W direction or N-S can be greater
18. What different kinds of forces led to the major deformed regions of the USA, such as the Basin and Range Province and the Appalachian Mountains?
Continental collision results in the formation of large mountain ranges, such as the present-day Himalayas of Asia, the Alps of Europe, and the Paleozoic Appalachian Mountains of eastern North America (Geology at a Glance, pp. 320-321). The final stage in the growth of the Appalachians happened when Africa and North America collided.
43. When did dinosaurs rule the Earth and when did they go extinct?
Dinosaurs appeared in Late Triassic time and became prominent land animals through the Mesozoic Era, wiped out the dinosaurs at the end of the Cretaceous Period. 250-66 MA
13. What is the Earth's rock cycle and what drives it?
Driven by plate tectonics Planet's internal heat and gravitational field together drive plate movements and generate plume- associated hot spots. Heat from the sub together with gravity drive wind, rain, ice, and currents. The succession of events that results in the transformation of Earth materials from one rock type to another, then another, and so on. // Igneous, sedimentary, metamorphic.
35. What are the major Eons of Earth history, and what are the major Eras of the Phanerozoic Eon?
EONS: From earliest life: Hadean, Archean, Proterozic, and Phanerozoic ERAS: From earliest: Paleaozoic, Mesozic, Caenozoic
25. Understand how energy varies with earthquake intensity, and the relationship between earthquake amplitude and the frequency of occurrence.
Earthquake intensity- degree of ground shaking Modified mercalli intensity (MMI) scale I (not destructive) to XII (highly destructive) Magnitude scale Amount of energy released from the seismic source (amplitude of ground shaking - amount of up and down or side to side) Height of the largest then adjust to account for weakening of waves as they travel Ricter scale - logarithmic scale for defining magnitude Number given = local magnitude Moment magnitude - most accurate Intensity scale Energy release by earthquakes Compare earthquakes to other energy-releasing events IE- atomic bomb
22. Understand what an earthquake is, and what the focus, epicenter, and hypocenter are.
Earthquake: A vibration caused by the sudden breaking or frictional sliding of rock in the Earth. Focus/hypocenter - where seismic waves begin Earthquake with faulting- focus is point where slip of fault initiates Point on the surface of the earth that lies directly above the focus as the earthquake's epicenter
After the Fukushima Daiichi nuclear power plane flooded
Emergency batteries died, so the reactor cooling system failed and the fuel ends overheat
The earthquake occurred where the Pacific Plate is colliding with the _______ plate that Japan is on.
Eurasian
19. In what kind of plate tectonic environments do faults and folds occur?
Folding, thrust faulting, and metamorphism occur continuously (in time) along convergent continent-ocean plate boundaries where ocean floor is descending beneath a continental margin adjacent to an island arc or continental margin arc (subduction zone).
17. What is the relationship between faults, folds, and the type of forces that create them?
Folds constitute the twists and bends in rocks. Faults are planes of detachment resulting when rocks on either side of the displacement slip past one another. Folds and Faults are both driven by natural forces, such as weather, gravity and natural disasters
10. What is metamorphic foliation and how does it form?
Foliation can give a metamorphic rock a striped or streaked appearance in an outcrop or can give it the ability to split into thin sheets Has foliated either bc its mineral have a preferred orientation or bc different minerals concentrate in different layers so rocks display alt dark colors and light colors Can be distinguished by grain size/nature of foliation
4. What are evaporites and how do they form?
From chemical sedimentary rocks - the products of saltwater evaporation Salt precipitation occurs where saltwater becomes supersaturated - it can't keep all the dissolved ions that it contains in solution. This situation happens because evaporation removes water from a water body faster than the rate at which new water enters. This process takes place in desert lakes and along the margins of restricted seas. For thick deposits of salt to form, large volumes of water must evaporate. Because salt deposits form as a consequence of evaporation, geologists refer to them as evaporites. The specific type of salt minerals comprising an evaporite depends on the amount of evaporation. When 80% of the water evaporates, gypsum forms; and when 90% of the water evaporates, halite precipitates.
What are the major principles of relative dating? Be sure you understand and can apply all of them to a complex geological outcrop, such as that shown in Figure 10.2a from your textbook.
Geologic time described in both relative and absolute terms Relative age Chronological order of geological events, processes. Absolute age (numerical age) Time before present - years to billions of years Relative ages are determined via field observation Principal of superposition Younger on top of older Sedimentary rocks, lava flows Principle of original horizontality Sediments deposited in flat (horizontal) layers tilting/folding indicates later deformation Principle of cross-cutting relations Cross-cutting feature is younger Faults, dikes, igneous intrusions Principle of inclusions Included rock is older Pebbles, cobbles, xenoliths Principle of faunal succession Evolutionary changes through time Fossil assemblages Relative ages are determined via field observation Multiple observations can unravel complex regions Diagram- sketch of outcrop (EXAM QUESTIONS)
6. How and where does coal form?
Is an organic sedimentary rock - consists of carbon rich relicts of plants and other organisms - Organic debris (guts of organisms) that settles along with other sediment is eventually buried. When lithified, organic-rich sediment becomes organic sedimentary rock. Coal can only form when vegetation is deposited in a low oxygen (low o2) environment Typically a swamp or more Plant decay
Which of the following about the earthquake that struck Japan March 11, 2011 is TRUE?
It was the largest to hit Japan in 1000 years It was 1000 times more powerful than the Haiti earthquake It was strong enough to knock the earth slightly off its axis Fatalities were primarily related to the tsunami that followed it
The March 11 earthquake lasted about
5 minutes
47. What is the "Anthropocene"?
A term used informally in reference to the past few thousand years, to emphasize that during this time, human society has modified the Earth System significantly.
32. What are unconformities?
An unconformity occurs when sedimentary layers are deposited on top of a surface of erosion or nondeposition. Three kinds of unconformities are recognized: nonconformities, disconformities, and angular unconformities Nonconformities arise when sedimentary strata are deposited on top of crystalline (metamorphic or igneous) rock. Disconformities occur when strata are deposited on top of an erosional surface that was horizontal at the time, so that layers above and below the unconformity are parallel. Angular unconformities arise when the new strata are deposited on top of older layers that have been tilted out of horizontality, so that, regardless of future tilting, layers on opposite sides of the unconformity are not parallel.
20. What are anticlines and synclines, and how do they form?
Anticlines Folds that have arch like shape in which limbs dip away from hinge Synclines Folds with a trough-like shape in which the limbs dip toward the hinge Monoclines Looks like the shape of a carpet draped over a stair Formation of folds Flexural-slip folds Stack of layers bends and slip occurs between the layers to accommodate the bending (similar to deck of cards) Passive-flow folds Form when the rock bheabes like weak plastic and slowly flows WHY? Some layers wrinkle up, buckle, in response to end-on compression Shear stress New slip on fault
The pacific tectonic plate is moving
As fast as your fingernails grow
39. What atmospheric component is necessary for Earth to have an ozone layer, and why should we care about the ozone layer?
Beginning of free oxygen (o2) in the atmosphere Evidence: banded iron formations Consequence: development of the ozone (O3) layer This layer acts as a filter to prevent too much of the harmful ultraviolet light in sunlight from reaching earth.
14. What is the difference between brittle and ductile deformation? Between stress and strain?
Brittle deformation: forming joints and the fault involved cracking and breaking rock Plastic deformation (or ductile deformation): when a rock changed shape without breaking
3. In what ways do the textures of sedimentary rocks (for example, grain size, sorting, angularity of the clasts) tell us about the depositional environment, such as the proximity to the source, how fast the water was flowing, etc.?
Terrestrial (non marine depositional) environments Oxygen in surface water or groundwater reacts with iron in the sediment to produce rust-like iron-oxide minerals, which give the sediment an overall reddish hue. Glacial Environments: Ice is solid - can move sediment of any size and gathers a lot of sediment as it moves When the ice finally melts away, the sediment that had been in or on the ice accumulates as glacial till. Till is unsorted and unstratified—it contains clasts ranging from clay size to boulder size all mixed together. Mountain Stream Environments: Fast moving water has the power to carry large clasts During floods- boulders/cobbles tumble down the streambed. Where slopes decrease and water flow slows, the larger clasts settle out to form gravel and boulder beds, while the stream carries finer sediments like sand and mud farther downstream. Sedimentary deposits of a mountain stream would, therefore, include breccia and conglomerate (both rounded fragments). Alluvial-fan environments: Mountain front- stream empties into a plane Arid climates- not enough water to flow continuously he stream deposits its load of sediment near the mountain front, producing a wedge-shaped apron of gravel and sand called an alluvial fan Deposition (Deposition is the geological process in which sediments, soil and rocks are added to a landform or landmark) takes place here because when the stream pours from a canyon mouth and spreads out into multiple channels, friction causes the water to slow down, and slow-moving water does not have the power to move coarse sediment. Sediment in alluvial fans may accumulate close to the source, so it will not have undergone much chemical weathering. Thus, sand layers still contain feldspar grains, for these have not yet weathered into clay. Alluvial-fan sediments become breccia, conglomerate, and arkose. Desert Environments: Dust gets carried away- well sorted sand in dunes and thick layers of well sorted sandstone River Environments: Transport gravel, sand, silt, and mud. The coarser sediment tumbles along the bed in the river's channel and collects in cross-bedded, rippled layers while the finer sediment drifts along, suspended in the water. This fine sediment settles out along the banks of the river, or on the floodplain, the flat land on either side of the river that water covers only during floods. On the floodplain, mud layers dry out between floods, so they develop mud cracks. River sediments lithify to form rippled sandstone, siltstone, and shale. Typically, coarser sediments occur in elongate bands, relics of river channels. Layers of fine-grained floodplain deposits surround the relict channels, so in cross section, the channel has a lens-like shape Lake Environments: Clay settle out to form mud on the lake bed When lithified turns into shale Deltas form at the entry from stream into standing water Coastal and Marine Depositional Environments Marine Delta Deposits: Reaches the mouth of the river, stops flowing, sediment settles out to build a delta of sediment out into the sea. Inc. many environments and changes in sea level = great variety of sedimentary rock types. Coastal Beach Sands: Leave delta - wander along coast Ocean currents transport sand along the coast (washes back and forth = well sorted and rippled) = medium grained sandstone with ripple marks = beach environment Shallow-Marine Clastic Deposits: Proceed offshore - shallow-marine environment - clastic sediments = fine grained, well sorted, well rounded silt, variety of organisms like mollusks and worms. So, if you see beds of siltstone and mudstone containing marine fossils, you may be looking at shallow-marine clastic deposits Shallow-Water Carbonate Environments: Little sand/mud enter is host for carbonate shells = carbonate sediment Shell fragments - reefs - transform into various kinds of limestone Deep-Marine Deposits: Only fine clay and plankton provide a source for sediment Produces finely laminated mudstones, and plankton shells settle to form chalk (from calcite shells) or chert (from silica shells) Deposits of mudstone, chalk, or bedded chert indicate a deep-marine origin.
9. How can metamorphism change a rock?
Solid-state - does not form by solidification of magma The change we mean a metamorphic rock contains new minerals that did not occur in the protolith and/or new texture Possess metamorphic minerals New minerals that grow in place within solid rock during metamor Can produce a group of minerals that make up the metamorphic mineral assemblage Metamorphic texture defined by the arrangement of their mineral grains
45. What important type of animal thrived during the Cenozoic Era?
Mammals
11. What does metamorphic "grade" mean? What's the difference between low-grade and high-grade metamorphic rocks?
Metamorphic grade = amount or degree of metamorphic change Depends on the temperature and pressure Temperature plays the dominant role in determining the extent of recrystallization and neocrystallization Low temps (250-400 c) = low grade rocks High temps (over 600) = high grade rocks In between these = Intermediate grade Grade inc. = courser grains Different conditions yield different metamorphic minerals
7. What is metamorphism and how does it occur?
Metamorphic rock forms when a pre-existing rock, or protolith, undergoes a solid-state change in response to the modification of its environment. This process is called metamorphism.
8. What are the most important factors that can lead to metamorphism of a rock?
Modification of environment: change in temperature or pressure application of stress exposure to hydrothermal fluids
44. What killed the dinosaurs? What is the evidence for this event? Why would such an event lead to such a widespread extinction?
Most likely a meteorite impact - 13 km-wide meteorite at the site of the present-day Yucatan Peninsula in Mexico K-Pg Boundary Event (K stands for Cretacous and Pg for Paleogene- the earliest period of Cenozoic Era) Walter Alvarez noted that a thin layer of clay interrupted the deposition of deep-sea limestone precisely at the K-Pg boundary. For a short time- all plankton died, only clay at sea. Contained iridium - element found in meteorites, tiny glass spheres, wood ash, shocked quartz Radiometric dating indicates that igneous melts in the crater formed at this time Caused destruction because dust, ask, and aerosols lofted into atmosphere transformed the air into haze that reflected incoming sunlight and photosynthesis became difficult
26. Know the relationships between earthquakes and plate tectonic processes and plate boundaries.
Most occur in seismic belt (seismic zones) - plate boundary earthquakes Divergent-boundary seismicity Mid-ocean ridges two oceanic plates form and move apart Forms two kinds of faults- normal and strike-slip Transform-boundary seismicity One plate slides past another without producing or consuming oceanic lithosphere - results in strike slip motion Convergent-boundary seismicity One plate subducts under another - bends causing normal faults to develop in the downgoing plate Convergent boundaries can host intermediate and deep earthquakes Occur in the downgoing slab as it sinks into the mantle, defining the sloping belt of seismicity called a Wadati-Benioff zone, occur for several resons: in response to stresses caused by shear between the sinking lithosphere plate and surrounding asthenosphere; in response to the pull exerted by the deeper part of the plate on the shallower part as the plate sinks; due to stress generated by the resistance that the subducting plate encounters as it pushes into the mantle below; due to volume changes that take place when olivine, a mineral in the plate, undergoes a phase change and collapses to form denser minerals under the extreme pressure that develops in deeply subducted lithosphere.
Which of the following was a consequence of the earthquake
Multiple large (M2-M7) aftershocks Huge fires An inland softwater lake Thousands of dead and missing people
The slower seismic waves that followed are called
S waves
27. Understand the reasons that seismic waves propagate through the Earth the way they do, including their curved path and the concept of "shadow zones."
Seismologists have determined that seismic waves travel at different speeds at different depths in the mantle. Between a depth of about 100 and 200 km in the mantle beneath the ocean floor, seismic velocities are slower than in the overlying mantle. This 100- to 200-km-deep layer is called the low-velocity zone (LVZ). Below about 200 km, seismic-wave velocities throughout the mantle increase progressively with depth Seismologists interpret the increase in velocity with depth to mean that mantle peridotite becomes progressively less compressible, more rigid, and denser with depth. At depths of between 410 km and 660 km in the mantle, seismic velocity increases in a series of abrupt steps This results in a different mineral with a more compact structure—a process called a phase change. Where such phase changes take place, the overall characteristics of mantle rock change, and seismic waves travel at a different velocity. Because of these seismic-velocity discontinuities, seismologists subdivide the mantle into the upper mantle (above 660 km) and the lower mantle (below 660 km). The lower portion of the upper mantle (between 410 and 660 km), in which several small seismic discontinuities have been recognized, is called the transition zone. The P-wave and S-wave shadow zones are areas at the surface where seismic stations will not receive either P-waves or S-waves, respectively. They tell us that there is a liquid layer, the outer core, beneath the mantle of the Earth and the depth of the boundary between the mantle and the outer core.
