Review Questions for
2nd Lecture Test
Earth History and Global Change
GEOL-1122 Spring 2015
Section #1 ‑ Deformation, Structures and Mountain Building
Readings ‑ Chapter 10
1) What is Structural Geology? What important information can be derived from the study of geologic structures?
2) Define stress and strain. What is the difference between directed and lithostatic stress? Describe the types of directed stress (compressional, extensional and shear).
3) Describe the three types of strain that result from stress. Which two types are most commonly used in determining the geologic history of an area? Name a geologic structure that is formed by each type.
4) What controls the style and degree of deformation or strain? Why does near-surface stress commonly result in brittle strain? In contrast, why do regional metamorphic rocks commonly display plastic deformation?
5) How is the 3‑dimensional orientation of a rock unit or structure measured? Why is this information important?
6) Compare and contrast the following geologic structures: anticline, syncline, monocline, basin, and dome. Which of these structures form by compressional stress and which form by vertical crustal movement?
7) Describe the four major types of faults (normal, reverse, strike-slip and thrust). Describe the stress type and orientation of stress that is responsible for each fault type.
8) Why are thrust faults and folds commonly found in the same area? Along which types of plate tectonic boundaries are these structures most common?
9) How does a fault differ from a joint? Describe three ways in which joints form. Are all joints formed by mountain building and crustal deformation? Why do joints and faults most commonly form near or in the upper crust?
10) The San Andreas Fault is a right‑lateral strike‑slip fault. What does this mean? Describe the movement of the western fault block on which southern California is located. Which type of stress is most important along this boundary?
11) How do horsts and grabens form? Which stress type is responsible for these structures? Name a location in the United States characterized by these structures.
12) Name and describe the three types of plate boundaries where mountain building is most common. Since all three are convergent boundaries, describe the type of stress and geologic structures that are most commonly found in these areas.
13) Define and describe Isostasy. Explain why isostatic rebound is important in the recent geologic history of the Appalachian Mountains and glaciated areas?
14) Define the following terms: strike, dip, plastic, brittle, elastic, columnar joints, sheeting, hanging and footwall blocks, terranes, orogeny and fold.
Section #2 ‑ Plate Tectonics
1) Describe some of the observations that Alfred Wegener and Alexander du Toit used to support their idea of Plate Tectonics and the supercontinents of Pangaea and Laurasia.
2) Describe how paleobiogeography is used as evidence for Plate Tectonics. List and describe specific examples which support the idea that the continents of South America and Africa were at one time joined.
3) When was the fit of the continents between South America and Africa first noticed? How can this fit be improved when these continents are joined and the present Atlantic Oceanic removed? Is this a valid assumption?
4) Name and describe several rock types that are used to determine paleoclimate data. Describe how paleoclimate data is used as evidence that the continents were located at different latitudes in the geologic past. In addition to movement of the continents, what other explanation can be used to describe the climatic changes recorded in the rock record of certain areas?
5) How is structural and rock age information used to support the Plate Tectonic Theory? Give specific examples of these correlations.
6) What is the Gondwana Sequence? Where is it found? How is it used as evidence of plate tectonics? Make a simple sketch and write a short description of the sequence.
7) What is paleomagnetism? Describe the information that is recorded by paleomagnetism. In which rock types is paleomagnetism best recorded? Be able to determine paleolatitudes and rotation of a continent using paleomagnetic data . Are paleolongitudes also recorded? Explain.
8) Describe sea-floor spreading. Where does it occur? List and describe the evidence that indicates sea-floor spreading occurs. Describe how oceanic crust changes with increasing distance from the central ridge or rise.
9) What are magnetic reversals? Describe how magnetic reversals are used with heat‑flow and age data to prove the theory of sea‑floor spreading.
10) What is the Ring of Fire? How does this feature also support the theory of Plate Tectonics? Name and describe the two most important types of plate boundaries that form this area.
11) What are Benioff Zones? How are they recognized? How do they support the theory of Plate Tectonics? Why does the angle of these seismic zones vary?
12) What is a mantle hot spot? How are these used as evidence of plate movement?
Describe how mantle hot spots can be used to estimate rates of plate movement? Give an example of a modern-day mantle hot spot.
13) What are some of the possible mechanisms responsible for plate movement? Which mechanism appears to be the most important? Describe the layers that are involved in this process.
14) Name two locations where we can directly measure the rate of plate movement. How fast do these plates move?
15) Name the three major types of plate boundaries. Describe the characteristics of each type. Name geographic examples for each of these.
16) Explain why the distribution of natural resources is largely controlled by plate tectonics.
17) Define the following terms: Plate Tectonics, island arcs, transform margin, seafloor spreading, Mesosaurus, Glossopterus, Curie Point, lithosphere, asthenosphere, low‑velocity zone, magnetic inclination, subduction zone, and mid‑oceanic rises and ridges.