Geo Oce Test 2
What are the differences between a submarine canyon and an ocean trench?
A trench os a result of plate tectonics while a canyon is a result of erosion.
List two conditions that improve an organism's chances of being preserved as a fossil.
Rapid burial and possession of hard parts
What is the cataclysmic event called in which an exploding star produces all of the elements heavier than iron?
Supernova.
What event is thought to have ended the reign of the dinosaurs?
The large carbonaceous meteorite that struck our planet 65 million years ago.
List and describe the different types of hydrothermal vents.
Warm-water vents: below 30C and generally emit water clear in color White smokers: Between 30C and 350C and emit water that is white because of the presence of various light-colored compounds, including barium sulfide. Black smokers: Above 350C and emit water that is black because of the presence of dark-colored metal sulfides, including lead, iron, nickel, copper, zinc, and chromium.
Describe the differences in earthquake magnitudes that occur between the three types of plate boundaries, and include why these differences occur.
Convergent: Deep focus earthquakes, Spreading centers (Shallow earthquakes (<10km deep)0, Trenches (can be near the surface to very deep, near subduction zones, get successively deepers away from the trench), Relentlessly pushed up against each other and the subducting plate bends as it goes below (thick crust stores more energy, mineral structure changes occur, causing a change in volume), Peru- Chile Trench Divergent: Shallow focus earthquakes (thinner crust stores less energy), Energy released is closely related to the spreading rate (faster spreading = less energy released), Mid- Atlantic Ridge, East Pacific Rise. Transform: Shallow but strong earthquakes ( cuts through continental crust, which is stronger than oceanic crust), San Andreas Fault
What was the source of water for the first oceans?
Outgassing of water vapor from the eruption of volcanoes.
Write a persuasive essay addressing the following statement, "Events during the Precambrian eon set the stage for multicelled life to evolve on Earth."
-For life you need water, protection, and minerals -Iron core formed: protects us from radiation (protection) -Atmosphere formed by outgassing (volcanos) (protection) -Oceans formed (liquified water) -Bacteria formed in extreme areas (hydrothermal vents, salt pools) -Oxygen was released. -Oxygen allowed for ozone layer to form (protection and more stable climate) -Because of the change in radiation, milti-celled life could form in the ocean
What evidence from the ocean crust helped formulate Plate Tectonic Theory?
-Magnetism and andternating polarity in the crust shows spreading as new crust is added (on each side of the speeding center) -Age of rocks (younger at the mid ocean ridge and get older as they spread out) -If you were to map out earthquakes they would show you the borders of plates (plate tectonic action) -Volcanic arcs shows low and where the plate moved based on the location of the hotspot
Describe the conditions under which carbonate oozes can exist below the CCD.
-When the carbonate ooze will settle on the top of the mid-ocean ridge. As seafloor spreading occurs, new sediment will be deposited on top of the ooze, and will be pushed below the CCD. Once sediment, is above the ooze, it protects it from being dissolved.
Angiosperms
125 million -1st angiosperms was aquatic
Pangea breaks apart
150 million
Birds
160 million
Oxygen (photosynthesis and banded iron)
2 billion
Mass extinction 4 (late triassic)
200 million -as short as 10 thousands years -75-80% of all species -Changes in sea level and ocean chemistry - lead to the appearance of the first dinosaurs and mammals
Modern humans
200 thousand
Apes
25 million
Mass extinction 3 (end permian)
250 million -biggest one 90% of all species -less than 100 thousand years
Bacteria appears
3.8 billion
Reptiles
315 million
Amphibians appeared
365 million
Mass extinction number 2 (lat devonian)
375 million -4 million years with 2 pulse -sea level lowered -climate change
Gymnosperms
380 million -Led to flowering plants -Animals could eat them
When did the continents start forming?
4 billion
When did the Earth form?
4.6 billion
Insects
415 million
Land plants
430 million -1st organisms to live their entire life cycle on land -mosses and liverworts because they didn't have the structure to hold themselves up
1st mass extinction
445 million -spanned 2 million years -evidence of climate change -only marine species because there was nothing on land
First fish (armor plated)
530 million
Gondwana broke up
540 million
1st primates
55 million -dominant land organisms
Mass extinction 5 (KT)
65 million -70-80% of both land and marine species -KT boundary is the layer of rock with iridium which is only found in meteors -extinction already happening before the meteor -took a long time -Angiosperms dominant after this -Allowed for mammals to take over
Muliticelled animals (Cambrian explosion)
680 million
Rodinia broke up
750 million (movement helped warm the Earth)
A mass of granite is in contact with a layer of sandstone. Using a principle description in the chapter, explain how you might determine whether the sandstone was deposited on top of the granite of the granite was intruded into the sandstone after the sandstone was deposited.
A depositional contact or unconformity would be proven if detrital rock and mineral grains from the granite were found in the sandstone. Also the granite just below the contact might show reddish discoloration or other evidences of having been weathered before the sandstone was deposited. Bedding in the sandstone will be parallel or nearly parallel to the contact; there will be no evidence for contact metamorphism in the sandstone; and the sandstone will not be cut by the granitic dikes. If the contact is intrusive, the sandstone may be cut by granitic dikes and may show contact metamorphism. Rock and mineral grains in the sandstone will not show any direct correlation to the granite, and bedding in the sandstone will probably not be parallel to the contact.
How can plate tectonics be used to help explain the difference between and seamount and a tablemount?
A seamount is a volcano with a cone-shaped top, whereas a tablemount is a volcano with a flattened top. Though both of these features originate at the crest (and topographic high) of the mid-ocean ridge, a tablemount has been subject to wave erosion when it rises above sea level. When the crust containing the tablemount is pushed away from the crest (and therefore onto a topographically lower position), or is moved away from a hot spot, it is re-submerged with its flat top.
Discuss how the chemical composition of Earth's interior differs from its physical properties. Include specific examples
According to the chemical properties, the Earth should only have a crust (silicate minerals), a mantle (high density iron and magnesium silicate rock) and a core (high density iron and nickel). According to the physical properties, the Earth has five layers, the inner core (rigid and does not flow), the outer core (liquid and capable of flowing), the mesosphere (is plastic but is rigid because of the pressure), the asthenosphere (it is plastic and extends to the base of the mantle) and the lithosphere (Earth's cool, rigid, outermost layer that includes the crust and the topmost portion of the mantle, it is brittle and the plates involved in plate tectonics are located in it).
Distinguish among angular unconformity, disconformity and nonconformity.
Angular unconformity: consisting of tilted or folded sedimentary rocks that are overlain by younger, more flat-lying strata. Disconformity: strata on either side are essentially parallel. Nonconformity: the break that separates older metamorphic or intrusive igneous rocks from younger sedimentary strata.
How can movement of continents trigger climate change?
As continents move, the patterns of ocean currents and global winds change, which influences the global distribution of temperature and precipitation.
Why is evolution of a type of bacteria that employed photosynthesis to produce food important to most modern organisms?
Because a byproduct of photosynthesis is oxygen, which is an essential gas for most organisms.
Why does a map of worldwide earthquakes closely match the locations of worldwide plate boundaries?
Because earthquakes are released stress along subduction and spreading zones, which happen along boundaries.
Why is most lithogenous sediment composed of quartz grains? What is the chemical composition of quartz?
Because it is the most abundant, chemically stable and durable mineral (SiO2).
How does the dip of magnetic particles found in igneous rocks tell us at what latitude they were formed?
Because the magnetite in the rock aligns itself according to the magnetic field while the magma/lave is still hot, so when it cools it is in the line. The degree of the dip increases with increasing latitude.
Why are amphibians not considered "true" land animals?
Because they need both water (aquatic environment) and land to survive.
Explain the stages of progression that result in calcareous ooe existing below the CCD.
Calcareous ooze may exist below the CCD when the calcareous sediments are covered by overlying non calcareous sediment. As a spreading mid-ocean ridge accumulates calcareous ooze when it is shallower, the calcareous ooze will be covered by pelagic clays when the flank of the mid-ocean ridge subsides beneath the CCD as plates continue to move farther apart.
Describe the environmental conditions (e.g. surface water temperature, productivity, dissolution, etc) that influence the distribution of siliceous and calcareous ooze.
Calcareous ooze: warmer surface seawater for production, cooler deeper seawater for dissolution; surface ocean productivity controlled by such factors as sunlight, length of seasons, abundance of nutrients. Siliceous ooze: cooler surface seawater for production, most important is surface ocean productivity controlled by sunlight, length of seasons,and especially abundance of nutrients. Siliceous ooze typically accumulates beneath areas of high biologic productivity associated with surface ocean upwelling.
List the two major chemical compositions of which most biogenous sediment is composed and the organisms that produce them. Sketch the organisms.
Calcium carbonate: Calcite. Foraminifera and coccolithophores. Silica: microscopic algae called diatoms and protozoans called radiolarians.
Contrast the philosophies of catastrophism and uniformitarianism. How did the proponents of each perceive the age of the Earth?
Catastrophism was the prevailing philosophy that guided people's' explanations of Earth prior to the time of Hutton. Catastrophists believed that Earth's landscape had been shaped primarily by great catastrophes. The philosophy of uniformitarianism, which was born with the writings of James Hutton in the late 18th century, stated that the same processes that mold Earth today shaped it in the past. Thus, in order to understand the past, one must understand the present. Catastrophism was a natural outgrowth of people's' view that Earth was created in 4004 B.C. (a figure derived from biblical interpretation). The creation of features of the natural landscape had to be tied to this shortage. In contrast, the acceptance of uniformitarianism meant accepting a very long history for Earth, for most processes take a great deal of time to create and destroy features.
What kinds of unusual life can be found associated with hydrothermal vents? How do these organisms survive?
Communities of clams, mussels, worms, and other organisms utilize the archaeon and bacteria oxidize that use hydrogen sulfide.
What are several reasons why diatoms are so remarkable? List the products that contain or are produced using diatomaceous earth.
Diatoms are microscopic, photosynthetic organisms with ornate cell walls. They reproduce both sexually and asexually, they exist as individual cells or colonial organisms, they are found in a diversity of habitats, and they are among the most abundant organisms on Earth. As primary producers in aquatic ecosystems, diatoms are at the base of the food chain in marine and freshwater environments. Perhaps most importantly, they are main source of O2 in the atmosphere. The main commercial uses for diatomaceous earth include: filters (sugar refinement, brewing, and swimming pool filters), mild abrasives (in such products as toothpaste, facial scrubs, and household cleaning and polishing compounds), absorbent (chemical spills and as pest control), chemical carrier (in paint and dynamite), optical quality glass (because of the pure silica in diatom cell walls),space shuttle tiles (because they are lightweight and provide good insulation), and additive in concrete
List and describe the three types of plate boundaries. Include in your discussion any seafloor features that are related to these plate boundaries, and include a real-world example of each. Construct a map view and cross section showing each of the three boundary types and direction of plate movement.
Divergent: found along ridges where new lithosphere is being added. Mid ocean ridge, rift valley, magma chambers, oceanic rise. The red sea is an example. Convergent: plates are moving together and one subducts under the other. Deep ocean trench, volcanic arc, continental arc, island arc, uplifting, earthquakes.. The Peru-Chile Trench is an example. Transform: Plates grind past one another. Transform faults. The San Andreas fault is an example.
Contrast the eastern and western margins of North America during the Cenozoic era in terms of their relationship to plate boundaries.
During the Cenozoic the eastern continental margin of North America was tectonically stable and the site of abundant marine sedimentation. The western margin, in contrast, was the leading edge of the North American plate. As a result, plate interactions during the Cenozoic gave rise to many events of mountain building, volcanism, and earthquakes in the West.
What subdivisions make up the geologic time scale? What is the primary basis for differentiating the eras?
Eons, Eras, Periods, Epochs. Fossils are the primary basis for differentiating between eras.
If you could travel back in time with three figures (illustrations) from this chapter to help Alfred Wegener convince the scientists of his day that continental drift does exist, what would they be and why?
Figure 3 because it shows how the continents fit together. Figure 5 because it shows climate, ice ages, as well as that in relation to Pangea. Figure 6 because it shows the fossil evidence.
Describe the process by which abyssal plains are created.
Fine particles of sediment slowly drifting onto the deep-ocean floor and settling out, forming a thick, even layer.
Discuss the development of bathymetric techniques, indicating significant advancements in technology.
For 2000 year s sounding (line with heavy weight) was used to measure the depth of the ocean. Challenger showed that the ocean floor was not uniform. In the 1900 they were using echo sounders that used times of pings to measure depth. WWII developed the precision depth recorder. Today we use multibeam echo sounders which use multiple beams of echo as well as sonar.
If siliceous ooze is slowly but constantly dissolving in seawater, how can deposits of siliceous ooze accumulate on the ocean floor?
If a layer of pelagic clay covers a layer of siliceous (silica-based) ooze, the ooze will dissolve more slowly. Also,if the rate of deposition of siliceous tests (shells) exceeds the rate that the tests dissolve, the silica ooze will build up over time
Assume that a hypothetical radioactive isotope has a half-life of 10,000 years. If the ration of radioactive parent to stable daughter product is 1:3, how old is the rock containing the radioactive material?
If the ratio is 1:3, then two half-lives have transpired, making the rock 20,000 years old.
Why are fossils such useful tools in correlation?
Index fossils became important tools because they provide a way to match fossils to the same age.
How does the lithogenous sediment originate?
It comes from preexisting rock and landmasses and is carried through processes of erosion.
If a deposit has a coarse grain size, what does this indicate about the energy of the transporting media that would produce such a deposit.
It requires a lot of energy because they are usually bigger.
Describe what is shown by a hypsographic curve and explain why its shape reflects the presence of active tectonic processes in Earth.
It shows the relationship to the height of the land to the depth of the ocean. The uneven distribution of area at different depths and elevations is proof that there is plate tectonics because without them it would be even.
List and describe the characteristics of the four basic types of marine sediment
Lithogenous: sediment that is derived from rocks. Pelagic, so it has to settle out of the water column and will be most prevalent far from land. So, lithogenous pelagic sediment can be wind-blown dust (this is called eolian sediment), volcanic ash, or other fine particles that were originally rocks. Lithogenous sediment dominates in deep areas such as the Pacific Ocean away from the East Pacific Rise. Biogenous: Biogenous sediment is derived from living organisms, normally planktonic organisms because they're the most abundant. Planktonic life comes in a variety of forms and species, but the kinds that form biogenous sediment are the kinds that have shells that are resistant to dissolution or destruction. The most common shell materials for plankton are calcite (CaCO3 or calcium carbonate) and opal (SiO2 or silica), and most biogenic marine sediment comes from four species as shown here: Hydrogenous: Some types of sediment are derived from the ions in seawater. Near hydrothermal vents, lots of metal ions are released into the water, and these ions oxidize or combine with silica and precipitate out as dark, metal-rich sediment. Manganese nodules are another form of hydrogenous sediments. Hydrogenous sediments are less common than lithogenous or biogenous sediments. They are almost never the dominant sediment type. Cosmogenous: The Earth is continually being bombarded from space by meteors and cosmic dust. Some of this material doesn't burn up in the atmosphere and reaches the oceans, where it can settle down to the ocean floor. Cosmogenous sediment is never a dominant type of sediment -- it is never more than a tiny fraction.
What group of animals is thought to have left the ocean to become the first amphibians?
Lobe-finned fish.
Describe manganese nodules, including what is currently known about how they form.
Manganese nodules are typically 5 cm in diameter although they may grow as large as 20 cm. They are made up of concentric layers of Mn oxides and Fe oxides around a nucleus. They tend to be found in deeper sea water where other sediments accumulate very slowly. The accumulation rate of Mn nodules is extremely slow, which makes it difficult to figure out how they form.
What are differences between a mid-ocean ridge and a hotspot?
Mid-ocean ridge: spreading center, divergent Hotspot: intraplate features (Volcanic island and Island chains), not near plate boundary
Explain why Precambrian history is more difficult to decipher than more recent geological history.
Most Precambrian rocks lack fossils, which hinders correlation of rock units. In addition, rocks this old are metamorphosed and deformed, extensively eroded, and frequently correlated by younger strata.
Why is lithogenous sediment that most common neritic deposit? Why are biogenous oozes the most common pelagic deposits?
Most marine sediments are mixtures of sediments from different source areas. Neritic deposits are mostly commonly lithogenous because sediments from land are most frequently deposited in the near shore marine areas. Biogenous components are overwhelmed by the amount of lithogenous material. In contrast, in pelagic deposits, biogenous oozes are the most common type of sediment because they are produced within the ocean itself. The biogenic sediments outweigh the amount of silt and clay transported into the oceans by wind and turbidity currents.
Using the paleogeographic reconstructions shown in Figure 38, determine when the following events first appear in the geologic record:
North America lies on the Equator. 300 million years ago The continents come together as Pangaea. 240 million years ago The North Atlantic Ocean opens. 180 million years ago India separates from Antarctica. 120 million years ago
Briefly describe the difficulties in assigning numerical dates to layers of sedimentary rock.
Not all rocks can be dated by radiometric methods, sedimentary rocks can rarely be dated by this method. The rock's age can't be accurately determined because the grains composing the rock are not the same age as the rock in which they occur. (weathering takes place)
What did plants have to overcome to move onto land?
Obtaining water and staying upright despite gravity and wind.
Convergent boundaries can be divided into three types based on the crust contained on the two colliding plates. Compare and contrast the different types of convergent boundaries, That result from theses collisions.
Oceanic Continental Convergence: Ocean plate is subducted, continental arcs generated, explosive andesitic eruptions. Oceanic Oceanic Convergence: denser plate is subducted, deep trenched generated, Volcanic island arc generated. Continental Continental Convergence: No subduction, Tall mountains uplifted.
Describe differences between granite and basalt. Which property is responsible for making the granitic crust "float" higher in the mantle?
Oceanic crust is composed of basalt, it is dark with a relatively high density and it originates from molten magma. Granite is a lower density (meaning it floats on the basalt) and it is lighter colored.
How do oozes differ from abyssal clay? Discuss how productivity, destruction, and dilution combine to determine whether an ooze or abyssal clay will form on the deep-ocean floor.
Oozes contain at least 30% biogenous particles (by weight); (in contrast to abyssal clay that contains less than 30% biogenous material. Most of the remaining percentage (up to 70%) of abyssal clay deposits is lithogenous clays.) Whether or not an ooze forms depends on the relative rates of biogenous and lithogenous particle depo sition in an area. The deposition rate of biogenous particles is a function of the rate at which they are produced (productivity) versus the rate at which they dissolve in ocean water (destruction). Silica dissolves slowly at all ocean depths, but calcium carbonate dissolves much faster in deeper water. If lithogenous soil deposits faster than biogenous does, the lithogenous concentration will "dilute" the biogenous, and ooze won't form.
Match the following words and phrases to the most appropriate time span, Select from the following: Precambrian, Paleozoic, Mesozoic, Cenozoic.
Pangaea came into existence: Paleozoic First trace of fossils: Precambrian The Era that encompasses the least amount of time: Cenozoic Earth's major cratons formed: Precambrian "Age of the Dinosaurs": Mesozoic Formation of the Rocky Mountains: Precambrian Formation of the Appalachian Mountains: Paleozoic Coal swamps extended across North America, Europe and Siberia: Mesozoic Gulf Coast oil deposits formed: Cenozoic Formation of most of the world's major iron-ore deposits: Precambrian Massive sand dunes covered a large portion of the colorado Plateau region: Mesozoic The "Age of Fishes" occurred during this span: Paleozoic Pangaea began to break apart and disperse: Mesozoic "Age of Mammals": Cenozoic Animals had hard parts that appeared in abundance: Precambrian Gymnosperms were the dominant trees: Mesozoic Stromatolites were abundant: Precambrian Fault-block mountains formed in the Basin and Range region: Cenozoic
Describe the major features of a passive continental margin: continental shelf, continental slope, continental rise, submarine canyon, and deep-sea fans.
Passive continental margin: Not located near a plate boundary, have very little activity. Continental shelf: a generally flat zone extending from the shore beneath the ocean surface to a point at which a marked increase in slope angle occurs. Coastal islands, reefs, and raised banks. Granitic continental crust. Continental slope: Where the deep ocean basin begins. Slope averages 4 degrees but can vary from 1-25. Continental rise: Transition zone between continental margin and deep ocean floor. Compiled of piles of debris from turbidity currents. Graded bedding, stacks of graded bedding are called turbidite deposits. Submarine canyon: V-shaped with branching tributaries. Deep-sea fans: Buildup of deposits that for continental rises.
What kind of information can be obtained by examining and analyzing core samples?
Past climates, ocean circulation, sea floor spreading, major extinctions,and nutrient supplies for marine organisms.
List and briefly describe at least five different types of fossils.
Petrified wood (wood turned into stone): fossilized wood where all the original wood has been replaced with minerals, while retaining the structure and all the features of the original piece of wood. Mold and Cast fossils: A mold fossil forms when an organism dies and its body is covered by layers of sediment. As time passes, the organism itself, particularly when composed primarily of softer materials, is eroded and carried away, leaving a negative imprint of its body. A cast fossil forms when a mold fossil is filled with some form of mineral, usually through the seepage of water depositing the minerals within the mold. In time, the mold is filled and the materials deposited harden, creating a replica of the original fossil. This is called a cast fossil. Thin carbon film: Over time, most of the chemicals in organic material (such as a living organism) evaporate away leaving only a thin carbon film copy of the organism behind. Impressions: An organism gets buried in a fine-grained sediment, the organism itself decays and evaporates away, but an impression of the organism is left behind and preserved in the sediment. Insect in amber: Insects become trapped in sticky plant resin (tree sap) and when the resin hardens, the insect is well protected. Corpolite: Fossilized fecal material
In which ocean basin are most ocean trenches found? Use plate tectonic processes to help explain why.
Results from collision of two plates along plate boundaries. Most are found in the Pacific ocean because that is where you have most of the convergent plates.
Why was the pattern of alternating reversals of Earth's magnetic field as recorded in the sea-floor rocks such an important piece of evidence for advanced plate tectonics?
Rock of the same age surrounding a plate boundary will therefore also have a similar magnetite orientation based on the magnetic field the earth had at the time it was formed. This shows that new rock is formed at the seafloor and is evidence of plate tectonics.
What is meant by the term correlation?
Rocks of similar age in different regions must be matched up.
Discuss the origin of the carious volcanic peaks of the abyssal plains: seamounts, tablemounts, and abyssal hills.
Seamounts: Volcanoes that are under water but are more than 1km above the sea floor. Tablemounts: Seamounts with flattened tops. Abyssal Hills: Less than 1000 meters tall but still under the sea floor.
What characteristics of marine sediment indicate increasing maturity? Give an example of a mature and immature sediment.
Sediment maturity increases as clay content decreases, sorting increases, non-quartz minerals decrease, and grains within the deposit become more rounded. This is dues to time. Glacial deposits are usually immature and beaches are usually mature.
Describe the difference between oceanic ridges and oceanic rise. Include in your answer why these differences exist.
Spreading rates (the total widening rate of an ocean basin resulting from the motion of both plates away from the spreading center) vary along the mid-ocean ridge and profoundly affect the slope of the mountain range. The faster the spreading rate, the broader the mountain range associated with the spreading center. The rapidly spreading and gently sloping portions of the mid-ocean ridge are called oceanic rises. The slower and steeper-sloped areas of the mid-ocean ridge are called oceanic ridges. Oceanic ridges and oceanic rises are both part of the global mid-ocean ridge system.
Describe the differences in origin between the Aleutian Islands and the Hawaiian Islands. Provide evidence the support your explanation.
The Aleutian Islands are part of a "volcanic arc" and are a continuation of the Aleutian Range of mountains on the Alaskan mainland. They lie at the boundary of the Pacific Plate and the North American Plate, and are formed by the subduction of the Pacific under the North American. They have no specific trend in age from one end to the other, with volcanoes forming at various times up and down their length. The Hawaiian Islands lie in the middle of the Pacific Plate, far from any of its boundaries. They have no connection whatsoever with any mainland features. They are formed by a 'hot spot' where a deep magma plume rises against the underside of the Pacific Plate, and are older and smaller as you go away from the hot spot, a situation brought about by the plate moving generally west-northwest over the plume. Some evidence is the fact that there are no plate boundaries anywhere near Hawaii, and the trend in age (and volcanic activity) with position.
Describe the K-T event, including evidence for it and its effect on the environment.
The K-T (Cretaceous-Tertiary) Event was presumably an asteroid impact and/or a massive volcanic eruption that spewed so much soil into the atmosphere that sunlight was blocked for a few months. This killed most photosynthetic plants in certain environments, which in turn killed the animals that fed on the plants, and then the animals that fed on those animals. Iridium, usually rare in terrestrial rocks, is found in abundance in some sediments deposited at the K-T boundary (ie the rock layer below which all dinosaur fossil exists). Alvarez and others (1980) speculated that the Iridium anomaly indicated that a meteor struck Earth and created much dust in the atmosphere. The sediments with high Ir also contained shocked quartz-- quartz subjected to high pressure and high temperature at Earth's surface. Alvarez and others theorized that the dust would have created global cooling which might have led to the extinction of dinosaurs. Evidence from cores retrieved from the Blake Nose revealed coarse-grained sediment attributed to the K-T meteorite impact crater in the Yucatan peninsula. The coarse grained sediment included tektites, shocked quartz, a piece of reef rock from Yucatan, and high Iridium values.
If a radioactive isotope of thorium (atomic number 90, mass number 232) emits six alpha particles and four beta particles during the course of radioactive decay, what are the atomic number and mass number of the stable daughter product?
The atomic number of the stable daughter product is 82, and the mass number is 208.
Describe the general relationship that exists among distance from the spreading centers, heat flow, age of the ocean crustal rock, and ocean depth.
The closest to the spreading center is the hottest and it is where the new rock is being formed, as you move away from the spreading center it gets cooler, the rock gets older and eventually it dips off unto a deep trench where it is subducted, melted and turned into new rock.
What is the supercontinent cycle?
The idea that rifting and dispersal of one supercontinent is followed by a long period during which the fragments are gradually reassembled into a new supercontinent with a different configuration.
What is the law of superposition? How are cross cutting relationships used in relative dating?
The law of superposition is a basic principle of relative dating. It states that, in an undeformed sequence of sedimentary rocks (or surface-deposited igneous rocks), each bed is older than the one above and younger than the one below. When faults or igneous intrusions cut through other rocks, they are assumed to be younger than the features they cut. This is a statement of cross- cutting relationships
What are differences between the lithosphere and the asthenosphere?
The lithosphere is rigid and brittle while the asthenosphere is plastic, and is therefore able to move (without it there would be no plate tectonics).
Describe the most common types of cosmogenous sediment and give the probable source of the particles.
The most common types of cosmogenous sediment are tektites, microscopic spherules composed of glassy silicate rock material, and space dust or micrometeorites composed primarily of Fe and Ni. Macroscopic meteorite material may be ejected from meteor impact sites on Earth. Cosmogenous material comes primarily from outer space.
How does the ocean remove carbon dioxide from the atmosphere? What role do tiny marine organisms, such as foraminifera, play?
The ocean removes carbon dioxide two was, the first being the photosynthetic organisms that live in the ocean, the second being the fact that carbon dioxide is very soluble in ocean water where it joins other atoms or molecules to produce various chemical precipitates. The carbon dioxide (in the form of calcium carbonate) is used by many organisms to make shells. When the organisms die their bodies sink and that carbon dioxide is trapped at the bottom of the ocean.
Cite the lines of evidence Alfred Wegener used to support him idea of continental drift. Why did scientists doubt that continents drifted?
The shorelines of the continents fit together to form Pangea. Rocks and mountain chains line up along where the continents would have fit together. There is evidence of glaciers in traditionally hot regions and coral fossils in Arctic regions. Fossils that could not have crossed the sea were found on different land masses. People disagreed with him because he thought that the continents plowed through the water and this was the reason that they formed mountains, the plowing was due to tidal shifts, but this contradicts physics.
How do fecal pellets help explain why the particles found in the ocean surface waters are closely reflected in the particle composition of the sediment directly beneath? Why would one not expect this?
The small particle common to pelagic sediment would require from 10 to 50 years to sink to the ocean floor, so the sediment on the ocean floor would not be expected to be similar to makeup of the particle concentrations in the surface water immediately above. The slightest current would be expected to carry them from 3000 to 15,000 kilometers (1860 to 9320 miles) laterally before they could reach the bottom. The fecal pellets incorporate small particles into larger packages that can sink to the ocean floor in 10 to 15 days, allowing the composition of bottom sediment to resemble closely the composition of the particle content of the surface water immediately above.
Explain how submarine canyons are created.
They are a result of the erosion power of turbidity currents.
Explain what graded bedding is and how it forms
They are layered sediment from turbidity deposits as things settle out.
What major development allowed reptiles to move inland?
They developed shell covered eggs that allowed them to reproduce on land.
Describe the process of how a drilling ship like the JOIDES Resolution obtains core samples from the deep ocean floor
This ship has a tall metal drilling rig to conduct rotary drilling. The drill pipe is made up of individual sections that can be screwed together to make a single string of pipe. The drill bit, located at the end of the pipe string, rotates as it is pressed against the ocean bottom. A core can then be raised to the surface from inside the pipe
Use pictures and words to describe differences between fracture zones and transform faults.
Transform faults are seismically active but fractures are not.
Most lithospheric plate contain both oceanic- and- continental- type crust. Use plate boundaries to explain why this is true.
When oceanic crust subducts under continental crust, some of it gets mixed together.
Why is radiometric dating the most reliable method of dating the geological past?
With careful sample collection and laboratory procedures, the radiometric methods consistently give accurate, reliable, absolute ages. The rate at which radioactive isotopes decay is constant and can be measured accurately. Also, no other method can be applied to all of geologic time. Fossils are accurate and reliable for Phanerozoic sedimentary rocks but are not found in most igneous and metamorphic rocks and are very rare in Precambrian rocks.
Why is Earth's molten, metallic core so important to humans living today?
Without the metallic core, the Earth would not have a magnetic field that protects the surface from thing such as solar winds.
