Please answer all seven questions. Keep your answers short and to the point.

7. What characteristics differentiate glacial lodgement till from glacial outwash? How are these characteristics related to the mode of origin of these materials?

Please answer all of the true-false questions – these are worth 2 points each.

Please answer 4 of 6 essay questions – these are worth 20 points each. Keep your answers short and to the point of the question.

True-false Questions:

1. In general, glacial lodgement till is more poorly sorted and more compact than glacial ablation till. T F

2. During periods of maximum advance of the continental ice sheets in the Wisconsin glacial epoch, global sea level stood nearly 150 meters higher than the modern day level.

T F

3. The world’s ocean basins lie at a lower average elevation than continents because continental crust is thinner and younger than oceanic crust. T F

4. As magma intrudes beneath an active volcanic system, the emplacement of molten material can be sensed by a decrease in the velocity of seismic waves that pass through the volcanic system. T F

5. In general, rocks at elevated temperature and confining pressure are less likely to behave in a brittle fashion. T F

6. Dispersive pressure is important in maintaining the fluidity of grain flows.

T F

7. The angle of internal friction of sandy, unconsolidated sediments is considerably reduced when the material is water-saturated. T F

8. In general, the bed load of streams consists of silt and clay size material, whereas the suspended load is made up of gravel and sand. T F

9. The discharge of a stream can be determined by measuring the cross-sectional area of the stream and multiplying that area by the average velocity of flow through the cross-section. T F

10. The record of glaciations in the Pleistocene is recorded much more completely by continental deposits, in contrast to the relatively incomplete record in marine sediments.

T F

Essay Questions: Answer 4 of 6

1.What is isostatic equilibrium? How does isostatic rebound following continental glaciation give us information about the behavior of the earth’s mantle?

2. The amount of ridge area in the oceans controls global sea level. Explain this relationship.

3. What is the Hjulstrom diagram? Why do clay-size sediments require higher flow velocities to erode than fine sand size sediment?

4. Describe the consequences of reduced sediment discharge in the Mississippi River system on the modern Mississippi Delta.

5. Why do crevasses rarely extend below a depth of 40 meters in glaciers?

6. How are stable isotope ratios of oxygen in marine calcium carbonate shells used to document changes in ocean temperature? How does the stable isotope ratio of seawater change during glaciation and deglaciation?

Name:_______________________

Please answer 5 of the seven questions that follow. Note that some questions are multipart.

1. What is the so-called hypsographic curve?

Why does the hypsographic curve, when presented in histogram form, have a strongly bimodal form?

2. What is the general relationship between global climate gradients and continental position? 

How have global climate gradients changed over that last 100 million years of earth history as a consequence of shifts in plate position?

3. What is a grainflow?

How is dispersive pressure important in grainflow systems?

4. What is stream discharge? 

What units are used? 

How is discharge measured?

5. Briefly describe the human-induced historical changes in the Mississippi River drainage basin over the last 200 years.

Discuss the impacts that result from changes in the flow of water and sediment through the system.

6. How are tectonism, mineral weathering, metamorphism, volcanism, and levels of atmospheric carbon dioxide interrelated?

7. How do the oxygen stable isotope ratios in marine carbonate sediment track the waxing and waning of continental glaciers and thus the warming and cooling of the earth at the middle and high latitudes?

Geology 210  

First Hour Exam – Makeup -  Thursday, February 27, 2003

 Name: ___________________

Please answer 5 of 7 questions (note that some are multi-part questions) – 20 points each:

1.  What is the general relationship between magma chemistry and eruptive style of volcanoes?  What factors account for this relationship?

2. What is the difference between a mud flow and a grainflow? Why are mudflows capable of moving over relatively low slopes at low velocities, whereas grainflows generally stop rapidly when the slope decreases?

3. Describe the difference between elastic and plastic deformation.

Why is elastic behavior thought to be important in earthquakes?

4.  What is a stream hydrograph? 

Sketch an example of a stream hydrograph that illustrates a stream with seasonal variation in discharge caused by spring snowmelt.  Be sure to label the axes with appropriate units and months of the year.

5.  How do crevasses illustrate the stress and strain relationships in moving glaciers?

Why are crevasses only found in the upper 40 meters or so of glaciers?

6.  Discuss the historical changes (last ~200 years) in the Mississippi drainage basin and the resultant impacts on the flow of water and sediment through the system.

7.  How are tectonism, mineral weathering, metamorphism, volcanism, and levels of atmospheric carbon dioxide related?