Midterm

Residence time =

Amount of substance/Net rate of addition or removal

Define what we mean by aspect ratio:

Aspect Ratio = Depth / Width

Oceanic crust, formed at seafloor spreading centers, along with continental crust comprise most of the lithospheric plates that ride atop the more plastic

Asthenosphere

T/F: The latent heat of vaporization is smaller than the latent heat of melting. (circle one)

False

T/F: The magnetic field of the Earth reverses itself each time that magma erupts from a mid-ocean ridge.

False

T/F: The oldest rocks are located at mid-ocean ridges.

False

Besides calcareous ooze, the other major type of biogenic ooze is called turbid ooze.

False (siliceaous ooze)

Use one of these two words in the following sentence: shallower, deeper Earthquakes are a form of energy release and can occur at different depths within the earth. Indeed, observations show that ____ earthquakes occur at continent-continent convergent zones or mid-ocean ridges than the earthquakes that occur at ocean-continental or ocean-ocean convergent zones.

Shallower

Professor Toomey is at it again. This time he wants to give you money and a research vessel to collect bathymetry data over the entire Atlantic Ocean. What does he mean by bathymetry (define it)?

The depth of the seafloor. Anything along those lines is acceptable.

The theory of continental drift explained much of the geologic evidence observed, setting the groundwork for the theory of plate tectonics. Explain what continental drift did not explain that led to it not being fully accepted:

Wegener's continental drift theory did not provide a mechanism for how the continents moved around the Earth. This was provided later in the theory of plate tectonics that combined continental drift with seafloor spreading and other lines of evidence.

Calculating the aspect ratio of an ocean basin allows us to compare its: (A) depth to width (B) depth to area (C) volume to surface area (D) sediment distribution

(A) depth to width

Biogenous sediments are derived from the inorganic parts of marine organisms. Typically, calcareous oozes are not found below a certain depth, which usually lies at an ocean depth of about (A) 4 m (B) 4 km (C) 40 km (D) 40 m

(B) 4 km

Continental arcs are volcano chains associated with plate boundaries that are: (A) oceanic-oceanic convergent (B) oceanic-continental convergent (C) continental divergent (D) oceanic divergent (E) continental-continental convergent

(B) oceanic-continental convergent

In terms of marine provinces, as you go from the OR coast offshore to the middle of the Pacific Ocean, you would cross these marine provinces (in order): (A) slope, shelf, abyssal hills, ridge (B) shelf, abyssal hills, ridge, slope (C) slope, shelf, ridge, abyssal hills (D) shelf, slope, abyssal hills, ridge

(D) shelf, slope, abyssal hills, ridge

The major process that destroys oceanic crust in plate tectonic theory is: (A) hydrothermal venting (B) seafloor spreading (C) echo-sounding (D) continental drift (E) subduction

(E) subduction

Paleomagnetism, the study of how Earth's magnetic field changes in time, was used to support the theory of plate tectonics in the late 20th century. Identify one more piece of evidence discussed in class used to support plate tectonics or continental drift, which laid the foundation for plate tectonics:

- fit of continents - earthquake distribution - glacier scours and striations - mountain chains continuous - sea floor spreading - fossil evidence across continents

The D/V Chikyu is currently off the coast of Japan collecting deep-sea sediment cores. It also measures bathymetry using a ship-mounted echosounder. Name one other method we discussed in class that scientists use to measure bathymetry:

- satellite altimetry - multibeam - soundings (direct measurement)

Type of plate boundary: 1. Active continental margin 2. Passive continental margin 3. Mid-ocean ridge

1. Convergent 2. Not a plate boundary 3. Divergent

Type of plate boundary Example 1. convergent 2. Divergent 3. Transform faults

1. HImalayas 2. Mid-Atlantic Ridge 3. San Andreas Fault

Deep ocean trenches are associated with: A. Subduction zones B. Transform faults C. Mid-ocean ridges D. Continental-continental convergent plate boundaries

A. Subduction zones

The correct order of marine provinces from the coast to the mid-ocean ridge is: A. shelf, slope, rise, abyssal plain B. slope, rise, shelf, abyssal plain C. abyssal plain, rise, slope, shelf D. rise, abyssal plain, slope, shelf

A. shelf, slope, rise, abyssal plain

You are given data from Doug Toomey, a professor in the Geology Department here at UO, that seems to show that the mid-ocean ridge at the East Pacific Rise is spreading faster than the one at the Mid-Atlantic Ridge. A. (1) According to what you learned in class, are his data correct? B. Draw a simple picture showing the difference in structure or cross-section between a rise (like the East Pacific Rise) and a ridge (like the Mid-Atlantic Ridge). Please label these clearly.

A: Yes, the EPR is moving faster than the MAR, which is reflected in its shape and structure below B: Image on docs

Hydrogen bonds form between neighboring water molecules because of: A. electron sharing B. polarity of water molecules C. electron transfer D. surface tension E. viscosity of water

B. polarity of water molecules

This quiz covers topics we talked about in Geological Oceanography. Name 2 of the other 3 major sub-disciplines of oceanography we identified in class:

Biological, chemical, or physical.

The seafloor magnetic pattern is best described as: A. not related to the location of oceanic ridges B. parallel to, but not symmetric about ocean ridges C. parallel to and symmetric about ocean ridges D. perpendicular to and symmetric about ocean ridges

C. parallel to and symmetric about ocean ridges

The type and amount of biogenic ooze found on the seafloor depends on all of the following EXCEPT : A. dilution B. productivity C. destruction D. wind

D. wind

List at least two differences between oceanic and continental crust that we discussed in class.

Density: oceanic crust is denser Type of rock: oceanic crust is mostly basalt, continental is granitic Color: oceanic crust is typically darker Formation: Oceanic crust is formed at sea-floor spreading centers Age: the oldest oceanic crust is ~200 million yrs old, while continental crust can be >3.8 billion Thickness: oceanic crust typically thinner, due to density

T/F: Oceanic crust, formed at seafloor spreading centers, along with continental crust, makes up the geologic zone known as the lithosphere.

FALSE (need crust plus upper mantle to make lithosphere)

Gravity corers, a type of sediment collection device discussed in class, can obtain cores that are longer than those obtained by the D/V Chikyu.

False

Lines of longitude run north-south on Earth and are called meridiens because they are all equidistant from each other.

False

There are four major types of marine sediments, such as biogenous. List the other three:

Lithogenous, cosmogenous, hydrogenous

Conservative

Long residence times, little or no change over time, occurs in constant proportions in seawater, examples include major constituents (Cl, Na, Ca, K)

The D/V Chikyu is capable of coring deep into the Earth. If the ship can drill through the crust at the ocean bottom, what layer (based on chemical composition) of the Earth will it penetrate into?

Mantle

How has seismic activity been used to improve our understanding of plate tectonic theory?

The occurrence and distribution of earthquakes has been used in support of the plate tectonic theory. In essence, the distribution of earthquakes follows plate boundaries, as this is where plates are colliding, slipping past each other, or diverging, which all cause earthquakes to occur. In addition, the depth of the earthquakes at that boundary tell us something about the type of plate boundary.

T/F: Lines of latitude run east-west on Earth and are all equidistant from each other.

True

T/F: Non-conservative properties change significantly over time, and include substances such as dissolved oxygen and biologically-active nutrients.

True

Spreading rate =

distance from mid-ocean ridge / age

Non-conservative

significant change over time, short residence times, variability over oceans, biologically active/reactive, examples include O2, CO2, nutrients