Questions for Geology 312 (modified January 2005)

I recommend that you try answering these questions either during or at the end of each of the 6 units of the course.  Please use the course notes and/or textbook as a resource, and please work with other students.  Let me know if you have any problems

Unit 1

 1.  The clay minerals are sheet-silicates.  Explain what this means about their atomic structure and the arrangement of their silica tetrahedra.

 2.  Draw simple cross-section diagrams of the clay minerals kaolinite and illite, using T-O notation to represent the tetrahedral and octahedral layers.

 3. Describe the chemical difference between illite and smectite and the implications of this difference to the behaviour of these minerals.

 4.  Describe the most common origin of clay minerals at the earth's surface in terms of what minerals they form from and how.

 5.  Name the three features of clay minerals that cause them to be strong absorbers of cations such as the heavy metals.

 6.  Describe what is happening when a smectite mineral swells, and discuss some of the geological implications of this swelling.

 7.  Explain why the temperature of the stratosphere is higher than that of the upper troposphere.

 8.  The output from the sun during the Archean was significantly less than it is now.  Explain why the temperature on the earth's surface was quite similar to what it is now.

 9.  Describe the wavelength differences between light emitted by the sun and that emitted by the warm surfaces of the earth.

 10.  List four greenhouse gases, in order of their contribution to the greenhouse effect.

 11.  Describe some natural and anthropogenic sources of atmospheric CO₂.

 12.  Explain how greenhouse gases work to keep the earth warm.

 13.  Explain the role of ocean currents in controlling the earth's climate, and give an example of how changes in current patterns could contribute to climate change. 

Unit 2

1.   Explain what the elastic rebound theory has to do with earthquakes.

2.   Explain the relationship between stress transfer and aftershocks.

3.   What parameters are used in the calculation of moment magnitude?

4.   Give several reasons why the damage from the 1985 Mexico quake was much worse in Mexico City than in some other cities which were situated much closer to the epicentre.  

5.   Draw a sketch of the plate distribution of our region, and explain  the origin of some of the earthquakes of this area.

6.   Describe the ways in which the 1946 Vancouver Island earthquake affected (a) buildings and (b) soils.

7.   Describe the effects of the 1964 Alaska earthquake in terms of subsidence and uplift.  Which areas were uplifted and which areas subsided?  Roughly how much uplift and subsidence was there?

8.   Prior to about 1985 it was widely considered that large (> M8) earthquakes did not occur on the Juan de Fuca (Cascadia) Subduction zone.  Describe some of the evidence that led to a change in thinking on this issue.

9.  Describe the plate tectonic setting of the December 26th 2004 Sumatra Earthquake

10.  The Sumatra earthquake and tsunami is described as the worst natural disaster in human history.  Give several reasons why it was so bad.

11.  Describe two important tools that can be used for predicting the general likelihood that an earthquake will occur in a particular area.  

12. If you were to buy a house in Nanaimo, what factors would you consider in order to be confident that it will not be badly damaged in a large earthquake.

Unit 3

1.   What are the typical ranges of SiO₂ in felsic, intermediate and mafic magmas, and how do these differences affect magma viscosity and eruption characteristics? 

2.   Explain the effects that exsolution of gases and crystallization of microlites have on magma viscosity.

3.   Why do magmas generated at subduction zones tend to be both more felsic and more variable than those from hot spots? 

4.   What tectonic process causes the opening of fissures on Iceland?

5.   Describe how the magmas erupted at Mt. Hekla can be more felsic (on average) than those of the mantle-plume magma which feeds this volcano. 

6.   The 1980 Mt. St. Helens lahars were derived from two different sources. Describe the timing and origins of these two types of lahars. 

7.   Upon what types of information did authorities base their decision to close the area around Mt. St. Helens in the spring of 1980?

8.  What was the evidence that volcanic activity was imminent at Mt. St. Helens in September 2004?

9.   To what can we attribute the cyclic nature of dome deformation and seismic activity at Montserrat in1996 and 1997?  

10.   Explain why volcanic eruptions on Hawaii are less dangerous to life than those at typical subduction-related volcanoes.

11. Describe the differences in the nature and the formation of pahoehoe and aa lava flows.

12.  Describe the general locations and geological origins of the three types of volcanism which are observed in British Columbia.

13.  Mt. Cayley hasn't erupted for around 200,000 years, and is not expected to erupt any time soon.  Explain why it is still considered to be a geological hazard.

14.  Name the three main gases which accompany volcanic eruptions.

15.  What happens (chemically) to volcanic SO₂ introduced into the atmosphere, and what is its net affect on global temperature? 

Unit 4

1.   Describe (in general terms) the variations in global temperature since the beginning of the Tertiary (65 m.y. ago) and since the beginning of the Quaternary (2.5 m.y. ago).

2.   Describe some of the factors that are considered as possible triggering mechanisms for the Pleistocene glaciation.

3.   Name and describe the 3 orbital and rotational elements of  the Milankovitch cycles, and explain how and why each can affect the global climate.

4.   What is a U-shaped valley, how does it form, and why is it significant to slope stability?

5.   Describe the diagnostic textural characteristics of a glacial till, and explain where lodgement till is formed with respect to the ice of a glacier.

6.   Glaciation produces a large amount of sediment in addition to till.  Name two other depositional environments associated with glaciers, and describe the types of sediments associated with them.

7.   Describe some of the factors that control soil formation. 

8.   Categorize the following terms with respect to the type of material that fails, and the rate of motion:

9.   What does the term angle of repose mean, and how is the angle of repose in unconsolidated materials affected by the water content?

10.  Explain why the existence of swelling clays can be significant to landslides.

11.  Give at least three reasons why slope failure is so common along the Sea to Sky Highway. 

12.  Describe some of the important geological features that contributed to the potential for failure at the Hope Slide site. 

Unit 5

1.   Explain why a magmatic nickel deposit could not exist in a felsic host rock.

2.   Why is there a difference in copper concentrations between volcanogenic massive sulphide deposits and sedimentary exhalative deposits?

3.   Describe the role of the intrusive body (ie. the porphyritic stock) in the genesis of a porphyry deposit.

4.   What sulphide mineral is common to most metal deposits, and what are the environmental implications of its widespread presence?

5.   Identify the ultimate source of the energy for the following energy resources: coal, geothermal, wind, hydro, tidal, nuclear.  

6.   What situation is essential in order for organic material to preserved long enough to form a coal deposit?

7.   Why is natural gas less of an environmental problem than oil, and oil less than coal?

8.   Explain why the low thermal conductivity of rocks can limit the longevity of a geothermal field.

9.   Explain why an unconsolidated clay deposit with porosity of around 50% might have a lower permeability level than a sand deposit with porosity of around 25%.

10.  Explain the difference between the “water table” and the “potentiometric surface”.

11.  Calculate the theoretical flow rate within an aquifer with a permeability of 0.01 cm/sec and a gradient in the potentiometric surface of 5 m (vertical) for every 100 m (horizontal).

12.  Using a cross-section diagram, show a cone of depression around a well, and how can it lead to one well going dry when another one near by is being pumped.

13.  Explain why iron-oxide minerals commonly precipitate at locations where groundwater comes to surface.

14.  What is the most common groundwater contaminant, and what are some of its sources?

Unit 6

1. What are the main contaminants within typical landfill leachate solutions?

2. What are the main gases released from a landfill?

3. What main geological criteria should be applied to the siting of a landfill?

4. What characteristics of the waste rock should be assessed in efforts to predict the acid-producing potential of a mine development?

5. What was the source of the metal contamination in the Myra Creek area at Buttle Lake in the late 1970's, and what has been done to eliminate this contamination?

6. Describe the system of multiple barriers which is proposed for nuclear waste disposal.

7. Why is disposal deep within the rocks of the Canadian Shield being promoted as a viable solution for the long-term disposal of nuclear waste?  

8. Two different areas have similar slopes (of between 40 and 60%), but one is well drained and the other is poorly drained. Based on the information in Table 6.1, what are the terrain stability classes of these areas?

9. Describe some of the features which may indicate that a slope has been or is prone to failure.

10. List some reasons why a logged slope might be more susceptible to failure than a similar unlogged slope.

11. What are the main reasons why forest road construction can lead to slope instability, and how can such instability can be minimized? 

12. What is one of the most important rock parameters to consider when planning a major road cut?

14. What types of rocks should not be used as aggregate for fill?

15. What types of rocks should not be used to make concrete?

16. Why might the Malaspina Cut have been cut to a ¼ to 1 slope as opposed to the designed ½ to 1 slope?