Exam 1 Flashcards
Define each of the following: lithosphere, asthenosphere, mesosphere. Which if them is believed responsible for the convection currents that move the tectonic plates?
L- outer brittle part, crust plus upper most part of mantle. As semi melted part if the mantle, has plasticity, M- rest of mantle going down to core. Asthenosphere responsible.
Give and briefly explain three different methods of learning about the structure and composition of the Earth below the crust.
Speed of earthquakes waves, composition of rocks erupted out in rift areas were there’s sea floor spreading, earths magnetic field, amount of heat escaping earth.
Where are submarine canyons found? How are they formed?
Submarine canyons are found off mouths of rivers, cut into cont slope. Formed by turbidity currents. Piled up sediments from river lets loose flows down canyons and erodes it.
Where are the deepest parts of the ocean basins? Are these near land, or in the center of basins? Explain
In subduction trenches/deep-sea trenches. Tend to be near land, found on plate margins were subduction is happening.
What kind of rock makes the continental crust? The oceanic crust? Which is thicker? Which is denser?
Granite. Oceanic: basalt. Cont is thicker, oceanic is denser.
What is the dividing line between the crust and mantle called? Is it deeper under continents or under ocean basins? Explain
The Moho. Deeper under continents, under mountain ranges with deep roots because it’s much thicker.
Give three lines of evidence cited by Wegener and other early proponents of continental drift to support the idea that Pangea had broken up, and that the continents were moving.
Puzzle pieces, coastlines can match, match up glacier striations from previous ice ages on either side of Atlantic, matching of geological formations across the oceans, (ENG – SCOT with Appalachia, Africa and Brazil) fossil evidence in different continents.
Are mid ocean ridges formed by compressional or tension forces? Would you expect to see the rocks buckled and folded near mid ocean ridges? Explain your answer.
Tensional. no, tension pulls apart.
How does the pattern of magnetic anomalies across mid ocean ridges support the idea of sea floor spreading?
Magnetic anomalies parallel to and symmetrical around mid ocean ridges, so when rock came up it had same orientation, but when spreads it has zebra stripes.
If new Ocean crust is being formed at mid ocean ridges, does this imply that the earth is increasing in diameter through time? Explain your answer
No, destroying crust at equal rate in subduction trenches. Add crust – destroy elsewhere at equal rate.
Give two examples of island arcs formed near subduction trenches. Given example of an island group formed by passage of a plate over a mantle plume. Which is more likely to be at the center of the plate? Explain your answer
Japan, Tonga, fiji, allusions, Philippines. Formed over mantle plume: Hawaii. Hawaii more likely to be the center of plate. Volcanic island arcs are at plate margins, not in Center.
Which of the following ocean basins has the most subduction trenches? The Pacific ocean, the Atlantic Ocean, the Indian Ocean, or the Arctic Ocean.
Pacific oceans, others don’t have subduction trenches.
What happened when two continental plate margins collide? When two oceanic plate margins collide? When a continental margin collides with an oceanic margin?
Crumble and form huge mountain ranges like Himalayas, 2 Oceanic collide, older colder subducted under younger one forming subduction trench. Cont and ocean, Cont overrides ocean and get subduction trench. Example juan De luca trench.
Given example of each of the following; it’s an embryonic ocean basin, a juvenile ocean basin, a mature ocean basin, a declining ocean basin, a terminal ocean basin.
Embry – African rift valley – no ocean but rift valley. Juvenile – Red Sea. Mature – Atlantic, Indian, Arctic. Declining – Pacific (decreasing in size), terminal- Mediterranean
What five physical and chemical features of water make it essential for life as we know it, and determine the patterns of life in seawater? From what chemical characteristics of water molecules do all these features to derive?
Water found in three forms in environ temps, solid water less dense than liquid water – ice floats. Has high thermal capacity, adhesion and cohesion. One of the best-known solvents for polar and ionic molecules. Fact that it is a polar molecule and polar covalent bonds.
What is the hydrological cycle? What physical feature of water makes it possible?
When you can evaporate water off oceans, carry over lands, rains, returns to ocean completing cycle.
Six different ions make up 99% of the dissolved ions in seawater. Give four of these ions. Are these ions considered the conservative or nonconservative ions of seawater?
Chart on page 4 of seawater. Sodium chloride, sulfite, magnesium, calcium. Conservative ions.
What is the principle of constant proportion, and how can it make it easier to calculate salinity?
Although salinity may vary, proportions of ions remain the same.
What are the major sources of salts in the oceans?
Weathering of rocks and volcanic eruptions
Give three major sinks for salts in the ocean.
Evaporates, fish poop, salts will absorb ions, blowing of Seaspray on land, removal of calcium and silicon to make shells of living organisms when they die they sink to the bottom.
Has the oceans salinity changed markedly for the past few billion years? Why or why not?
No. It’s in steady state equilibrium, amount of salts entering via sources equal to amount leaving via sinks.
Which has a longer residence time in the oceans, Na + or Ca 2+? Why?
Sodium (Na), calcium short- cuz constantly being used by living organisms to make shells.
What effects does salinity have on the density of water? It’s freezing point?
More salty the more dense the water. Increase salinity= lowers freezing point.
What is the thermocline? Will it be more pronounced in the tropical ocean or in the high latitude ocean? Explain
Range of depths where temperatures change rapidly with depths. More pronounced in tropical oceans because surface water is much warmer and overlies deep cold water.
At what latitudes, equatorial, subtropics, or polar, will the salinity of the surface water be the highest? Explain
Subtropics 30° n/a latitude because of high-pressure area, evaporation the greatest of those lats.
Does the salinity of surface water or deep water show more variation? Explain
Surface water shows greater variation, exchanges with atmosphere, adds salinity or looses salinity.
Which is denser, warm or cold water? Saline or fresh water?
Cold is denser, sailine is denser.
What is the picnocline? Will it be more pronounced at 30° North and South latitude, or at 70° north and south? Explain
Change in density with depth. More pronounced at 30° north – south, due to surface water being warmer.
Below the surface of the water, what is the major factor determining the concentrations of O2 and CO2? Which is more soluble in water?
Activities of living organisms, decomposing ones remove oxygen, ones doing photosynthesis will add oxygen. Carbon dioxide is more soluble.
Between what latitudes do the trade winds blow? The westerlies? How are these persistent winds created?
Trades – 30 north/south of equator, westerlies – 30 n/s – 60 N/South, creating zones of high and low pressures, low equator where air rises, high at 30° where are sinks. Winds blow from high to low pressure.
Between what latitudes do the Hadley convection cells operate? The ferrel cells?
Hadley 30 to equator, ferrel 30–60 (westerlies)
In what direction will coriollis deflection move air or water in the northern hemisphere? The southern hemisphere?
Northern hemisphere – clockwise/ right. Southern hemisphere – counter clock – left.
