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Study Quiz 3
Questions for quiz:
List 2/3 lines of evidence for Pleistocene Glaciations.
What did Agassiz use as his evidence to convince other geologists that there had been past "ice ages" or glaciations?
Moraines are geomorphic features that result most directly from:
a. Glacial advances
b. water movement
c. plate tectonics
d. thermohaline circulation
Moraines form:
a. at the leading edge of glaciers
b. along the sides of glaciers
c. both a and b
d. neither a nor b.
Foraminifera are microscopic organisms in the oceans that produce calcite shells. Which suite of foraminifera appear most useful for climate research on the advance/retreat of global ice sheets:
a. benthic
b. planktic
c. nether
d. both
The d18O of forams is in equilibrium with the ocean waters surrounding the organisms during their lives. Which of the following statements is true:
a. As the global ice volume increases, the d18O of forams will decrease (becoming more negative)
b. As the global ice volume increases, the d18O of forams will increase (becoming less negative)
Match the period of each cycle (100 ka, 40 ka, 23 ka)
a. Changes in the elliptical orbit of the Earth
b. Changes in the amount of tilt of the Earth’s spin axis
c. Precession of the Equinoxes
The Precession of the Equinoxes is the combined product of two precessional cycles. List the two:
1. _________________________________________________
2. _________________________________________________
T/F:
______ gravitational pull of other planets in the solar system affects variations in the shape of the elliptical orbit of the Earth around the sun
______ the positions of the solstices and equinoxes in relation to the eccentric orbit are fixed.
______ gravitational pull of other planets in the solar system affects variations in the tilt of the Earth’s spin axis.
______ the tilt of the Earth’s spin axis varies between 0 and 90 degrees on a 41,000 year cycle
______ the Perihelion refers the period when the Earth passes closest to the sun during it’s orbit
______ the Precession of Earth’s orbit, or the migration of the elliptical orbit as a whole, completes a cycle every 100,000 years.
The tilt of the earth’s spin axis:
a. changes in degree of tilt between about 22.2 degrees and 24.5 degrees
b. completes a cycle every 41,000 years
c. both a and b
d. neither a nor b
The Precession of the Earth’s ellipse (i.e., the migration of the elliptical orbit as a whole):
a. is a smooth cycle
b. completes a cycle every 413,000 years
c. both a and b
d. neither a nor b
Briefly describe the Orbital Monsoon hypothesis.
Which of the following is NOT TRUE about Monsoon circulations?
a. They are a result of differential heating of oceans versus land
b. They are linked to changes in the strength of solar radiation during summer and winter
c. They have been stronger or weaker at times in the past
d. They have remained relatively stable since the uplift of the Tibetan Plateau
Mediterranean sea sediments contain black, organic rich layers (sapropels, or "stinky muds")that were produced:
a. when strong monsoons occurred
b. when the Nile River had lower flows
c. when weaker monsoons occurred
d. when dinosaurs died and remains were buried in the Mediterranean
Changes in the amount of fresh water diatoms buried in the sediments of tropical Atlantic are evidence of:
a. changes in ice sheet advance and retreat over the African continent
b. changes in strength of the North African monsoon
c. the influence of the 41,000 year Milankovitch cycle
d. all of the above
Describe two lines of evidence that support the Orbital Monsoon hypothesis.
List two possible "amplifiers" that may explain how the subtle changes in Earth’s orbital parameters during the Pleistocene could have had such strong impacts on Glacial – Interglacial cycles throughout the Pleistocene, especially on the 100,000 year cycle.
State whether each of the following "feedbacks" affecting CO2 concentrations in the atmosphere are Positive (P) or Negative (N).
_____ Biological pump of the surface ocean
_____ increased nutrients supplied to the oceans
_____ Coral Reef hypothesis
_____ Terrestrial biomass production
_____ Cloud albedo
Salt marsh vegetation zonation is largely determined by 2 physical components:
1. ____________________________; 2. __________________________
Tides experienced on the Earth are largely a result of:
a. the Sun’s gravitational pull on the Earth
b. the Moon’s gravitational pull on the Earth
c. the centrifugal pull on the water as the Earth and Moon revolve around a common center of gravity
d. all of the above
Define the term "Barycenter" and explain its importance in the creation of tides on Earth.
Which of the following statements is NOT TRUE about Neap tides
a. they are lower tides than the average
b. they occur two times a month
c. they occur when the sun, moon and earth are aligned in a straight line.
d. they can produce even more reduced tidal ranges when apogee, aphelion and the 1st or 3rd quarter moon coincide.
List 3 constraints on plant life in a tidal marsh:
1.__________________________________________________________
2.__________________________________________________________
3.__________________________________________________________
Which of the following statements is NOT TRUE about the San Francisco Estuary:
a. it drains a little less than half of CA
b. it results from geologic constrictions at the Golden Gate and at the Carquinez strait
c. a natural salinity gradient extends from the Golden Gate to the Delta
d. it has existed as an estuary for the last 20,000 years.
Why is the fact that the CA coastline is an active continental margin important to understanding possible past extents of tidal marshes (like during the Last Glacial Maximum)
Which statement is the MOST TRUE about using stable carbon isotopic values of marsh organic sediments:
a. they can give a measure of the presence of C4 plants which occupied the marsh in the past.
b. They measure past marsh soil salinity
c. They are more precise than pollen analysis
d. They measure the total presence of C3 plants which occupied the marsh in the past
Of the three photosynthetic pathways (C3, C4 and CAM), which has the highest d13C values (hint: least negative)
About how long ago did the tidal marshes begin forming around the Estuary? Explain why they didn’t form earlier during the Holocene.
State the importance of using pollen analysis of marsh cores to detect changes in Pickleweed abundance.
Have sedimentation rates remained stable throughout the Estuary marshes during the last 5,000 years?
In the context of Global Warming, why should we be concerned with past events like the catastrophic Melt Water Event that occurred ca. 14,000 years ago?
In Pollen data from the marsh cores, which of the following is MOST TRUE:
a. C3 plants have pollen that all looks the same
b. C4 plants have pollen that looks the same
c. Increases in Pickleweed suggest decreased salinity on the marsh
d. Increases in Sedge pollen tend to overlap with increases in Pickleweed pollen
1. Which of the following were NOT lines of evidence used by L. Agassiz in the mid 1800s to argue for the existence of a past "ice age" or glaciation: 2 pts
a. presence of large boulders, called "erratics"
b. piles of unsorted rock debris called "moraines"
c. changing amount of 18O in glacial ice
d. linear scars on rocks called "striations"
2. Moraines are geomorphic features that result most directly from: 2 pts
a. Glacial movement
b. water movement
c. plate tectonics
d. thermohaline circulation
3. Foraminifera are microscopic organisms in the oceans that produce calcite shells. Which suite of foraminifera appear most useful for climate research on the advance/retreat of global ice sheets: 2
a. benthic
b. planktic
c. neither
d. both
4. True/False: 10
______ gravitational pull of other planets in the solar system affects variations in the shape of the elliptical orbit of the Earth around the sun
______ the positions of the solstices and equinoxes in relation to Earth’s eccentric orbit are fixed.
______ the tilt of the Earth’s spin axis varies between 0 and 90 degrees on a 41,000 year cycle
______ gravitational pull of other planets in the solar system affects variations in the tilt of the Earth’s spin axis.
______ the Perihelion refers the period when the Earth passes closest to the sun during its orbit
5. The Precession of the Earth’s ellipse (i.e., the migration of the elliptical orbit as a whole): 2
a. refers to the orbit of the moon around the Earth
b. completes a cycle every 413,000 years
c. both a and b
d. neither a nor b
6. Mediterranean sea sediments contain black, organic rich layers (sapropels, or "stinky muds") that were produced: 2
a. when strong monsoons occurred
b. when the Nile River had lower flows
c. when weaker monsoons occurred
d. when dinosaurs died and remains were buried in the Mediterranean
7. The dominant periodicity of glacial – interglacial fluctuations is 100,000 years, but the changes in solar insolation from the orbital parameters on this timescale are subtle. Which of the following is NOT TRUE about possible positive feedback (amplifier): 2
a. the Earth’s surface albedo could provide an amplifier
b. changes in the concentration of CO2 in the atmosphere could provide an amplifier
c. neither a nor b
d. both a and b
8. State whether each of the following postulated "feedbacks" affecting CO2 concentrations in the atmosphere are Positive (P) or Negative (N). 2
_____ Biological pump of the surface ocean
_____ increased nutrients supplied to the oceans
_____ Coral Reef hypothesis
_____ Terrestrial biomass production
_____ Cloud albedo
9. Which of the following best defines the term "hydroperiod" 2
a. the depth, frequency, and duration of flooding at a site on a marsh surface
b. the duration only of flooding at a site on a marsh
c. the salinity of the water on the marsh
d. the mixed diurnal tide cycle
e.
10. Tides experienced on the Earth are a result of: 2
a. the Sun’s gravitational pull on the Earth
b. the Moon’s gravitational pull on the Earth
c. the centrifugal pull on the water as the Earth and Moon revolve around a common center of gravity
d. all of the above
11. Which of the following statements is NOT TRUE about Spring tides 2
a. they produce a lower range of tides than the average
b. they occur two times a month
c. they occur when the sun, moon and earth are aligned in a straight line.
d. they can produce even more extreme tidal ranges when perigee and perihelion coincide with either the full or new moon.
12. List 3 plant adaptations for living in a tidal marsh: 6
1.__________________________________________________________
2.__________________________________________________________
3.__________________________________________________________
13. Which of the following statements is NOT TRUE about the San Francisco Estuary: 2
a. it drains 80% of CA
b. it results from geologic constrictions at the Golden Gate and at the Carquinez strait
c. a natural salinity gradient extends from the Golden Gate to the Delta
d. marshes began forming around it around 5,000 - 6,000 years ago
14. Which statement is NOT TRUE about using stable carbon isotopic values of marsh organic sediments as a proxy for past conditions: 2
a. they can give a measure of the presence of C4 plants which occupied the marsh in the past.
b. They cannot easily be used to distinguish the salt tolerant Pickleweed from common C3 plants
c. They can give a direct and accurate measure of past estuary salinity
d. The measurements need to be made on a mass spectrometer.
15. Which of the following general statements about the paleo-history of San Francisco Estuary marshes is NOT TRUE 2
a. the marshes did not form at the same time throughout the Estuary
b. many of the marshes have periods of high sedimentation
c. the salinity of the Estuary has been the same throughout the last 3,000 years
d. marshes near the Sacramento-San Joaquin are fresh tidal marshes, while those closer to the Golden Gate are salt tidal marshes
TOTAL POINTS 42
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