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12.1: Introduction - Geosciences

12.1: Introduction - Geosciences


Module 12

Streams and Floods

Figure 1. -Rick Obst

Introduction

Think about how many times a day you take water for granted— you assume the tap will be flowing when you turn on your faucet, you expect rainfall to water your lawn, and you may count on water for your recreation. Not only is water necessary for many of life’s functions, it is also a considerable geologic agent. Water can sculpt the landscape dramatically over time both by carving canyons as well as depositing thick layers of sediment. Some of these processes are slow and result in landscapes worn down over time. Others, such as floods, can be dramatic and dangerous.

What happens to water during a rainstorm? Imagine that you are outside in a parking lot with grassy areas nearby. Where does the water from the parking lot go? Much of it will run off as sheet flow and eventually join a stream. What happens to the rain in the grassy area? Much of it will infiltrate, or soak into the ground. We will learn about both surface water and groundwater in the next two modules. Both are integral parts of the water cycle, in which water gets continually recycled through the atmosphere, to the land, and back to the oceans. This cycle, powered by the sun, operates easily since water can change form from liquid to gas (or water vapor) quickly under surface conditions. Both surface water and groundwater are beneficial for drinking water, industry, agri- culture, recreation, and commerce. Demand for water will only increase as population increases, making it vital to protect water resources both above and below ground.

Select an image to view larger

Figure 2. Chesapeake Bay Virginia National Estuarine Research Reserve. Aerial view of Taskinas Creek area showing the very low gradient, meandering tidal streams.

Figure 3. Looking down a waterfall in Pant Glas, Scotland. The constant flow of water has cut the rock smooth and created small stepped pools.

Figure 4. Flash floods, like this one in the Gobi Desert of Mongolia, are common across the Southern United States, as well.

Figure 5. A weir was built on the Humber River (Ontario) to prevent a recurrence of a catastrophic flood.

Figure 6. Flooded street in Cedar Rapids, IA

Figure 7. USGS personnel monitoring flood waters in Waverly, Iowa.

Module Objectives

At the completion of this module you will be able to:

  1. Explain the hydrological cycle and residence times of water in its various compartments.
  2. Describe a drainage basin and different types of drainage patterns.
  3. Explain how streams form, how they are graded, and how flow velocity and sediment size are related to erosion and deposition in a stream channel.
  4. Describe the process of stream evolution and the types of environments where one would expect to find straight-channel, braided, and meandering streams.
  5. Describe examples of processes that lead to flooding.

Activities Overview

See the Schedule of Work for dates of availability and due dates.

Be sure to read through the directions for all of this module’s activities before getting started so that you can plan your time accordingly. You are expected to work on this course throughout the week.

Read

Physical Geology by Steven Earle

  • Chapter 13 (Streams and Floods)

Module 12 Quiz

10 points

Module 12 Quiz has 10 multiple-choice questions and is based on the content of the Module 12 readings and Assignment 12.

The quiz is worth a total of 10 points (1 points per question). You will have only 10 minutes to complete the quiz, and you may take this quiz only once. Note: that is not enough time to look up the answers!

Make sure that you fully understand all of the concepts presented and study for this quiz as though it were going to be proctored in a classroom, or you will likely find yourself running out of time.

Keep track of the time, and be sure to look over your full quiz results after you have submitted it for a grade.

Your Questions and Concerns…

Please contact me if you have any questions or concerns.

General course questions: If your question is of a general nature such that other students would benefit from the answer, then go to the discussions area and post it as a question thread in the “General course questions” discussion area.

Personal questions: If your question is personal, (e.g. regarding my comments to you specifically), then send me an email from within this course.


100 12.1 INTRODUCTION

Rural areas cover a multitude of natural and cultural landscapes, activities, and functions, including not only villages and agricultural areas, ranging from traditional to intensivemonoculture systems, forests, various parks, and wilderness, but also services and commercial sites, as well as educational and research centers. Specifically, rural areas provide living space for their inhabitants and for flora and fauna and, as buffer zones, fulfill significant balance functions between unpopulated wilderness zones and overloaded centers of dense development. Because of this complex diversity, our understanding of rural areas must consider more than how land is used by nature and humans. That is, our understanding must also encompass the economic and social structures in rural areas in which farming and forestry, handicraft, and small, middle, or large companies produce and trade, where services, from the most local to the most international (such as tourism), are provided. In addition, some rural areas represent valuable ecological balance zones through preservation and/or conservation establishments. All these factors create and evolve into a tight interdependence, interconnection, and competition.
Yet, today, over 54 percent of the world population (7,536 million)1 lives in urban areas and the proportion of the urban population is growing at a rapid rate. Thus, urbanization is one of the most important geographic phenomena in today’s world. Towns and cities are in constant flux. Historically, cities have been influenced by technological developments such as the steam engine, railroads, the internal combustion engine, air transport, electronics, telecommunications, robotics, and the internet. As the result of the global shift to technological-, industrial-, and service-based economies, the growth of cities and urbanization of rural areas are now irreversible. Moreover, another phase of transformation is under way, involving global processes of economic, cultural, and political changes.
Within the cities of the developed world, the economic reorganization has determined a selective recentralization of residential and commercial land use connected especially with a selective industrial decentralization. In contrast to the core regions, where urbanization has largely resulted from economic growth, the urbanization of peripheral regions has been a consequence of demographic growth, generating large increases in population (overurbanization) well in advance of any significant levels of urban or rural economic development. Luxury homes and apartment complexes, corresponding with a dynamic formal sector of the economy, contrast sharply with the slums and squatter settlements of people, working in the informal (not regulated by the state) sector.


12.1 Waves and Wave Processes

Particle motion within a wind-blown wave. Wind blowing over the surface of water transfers energy to the water through friction. The energy transferred from wind to water causes waves to form. Waves move as individual oscillating particles of water. As the wave crest passes, the water is moving forward. As the wave trough passes, the water is moving backward. To see wave movement in action, watch a cork or some floating object as a wave passes.

Aspects of water waves, labeled. Important terms to understand in the operation of waves include: the wave crest is the highest point of the wave the trough is the lowest point of the wave. Wave height is the vertical distance from the trough to the crest and is determined by wave energy. Wave amplitude is half the wave height , or the distance from either the crest or trough to the still water line. Wavelength is the horizontal distance between consecutive wave crests. Wave velocity is the speed at which a wave crest moves forward and is related to the wave&rsquos energy. Wave period is the time interval it takes for adjacent wave crests to pass a given point.

Diagram describing wave base.

The circular motion of water particles diminishes with depth and is negligible at about one-half wavelength , an important dimension to remember in connection with waves. Wave base is the vertical depth at which water ceases to be disturbed by waves. In water shallower than wave base , waves will disturb the bottom and ripple shore sand. Wave base is measured at a depth of about one-half wavelength , where the water particles&rsquo circular motion diminishes to zero. If waves approaching a beach have crests at about 6 m (

20 ft) intervals, this wave motion disturbs water to about 3 m (

10 ft) deep. This motion is known as fair- weather wave base . In strong storms such as hurricanes, both wavelength and wave base increase dramatically to a depth known as storm wave base , which is approximately 91 m (

Waves are generated by wind blowing across the ocean surface. The amount of energy imparted to the water depends on wind velocity and the distance across which the wind is blowing. This distance is called fetch . Waves striking a shore are typically generated by storms hundreds of miles from the coast and have been traveling across the ocean for days.

Model of a wave train moving with dispersion. Winds blowing in a relatively constant direction generate waves moving in that direction. Such a group of approximately parallel waves traveling together is called a wave train . A wave train coming from one fetch can produce various wavelengths. Longer wavelengths travel at a faster velocity than shorter wavelengths, so they arrive first at a distant shore . Thus, there is a wavelength - sorting process that takes place during the wave train &rsquos travel. This sorting process is called wave dispersion.

12.1.1 Behavior of Waves Approaching Shore

Types of breakers On the open sea, waves generally appear choppy because wave trains from many directions are interacting with each other, a process called wave interference. Constructive interference occurs where crests align with other crests. The aligned wave height is the sum of the individual wave heights, a process referred to as wave amplification. Constructive interference also produces hollows where troughs align with other troughs. Destructive interference occurs where crests align with troughs and cancel each other out. As waves approach shore and begin to make frictional contact with the sea floor at a depth of about one-half wavelength or less, they begin to slow down. However, the energy carried by the wave remains the same, so the waves build up higher. Remember that water moves in a circular motion as a wave passes, and each circle is fed from the trough in front of the advancing wave. As the wave encounters shallower water at the shore , there is eventually insufficient water in the trough in front of the wave to supply a complete circle, so the crest pours over creating a breaker.

All waves, like tsunamis, slow down as they reach shallow water. This causes the wave to increase in hight. A special type of wave is called a tsunami , sometimes incorrectly called a &ldquotidal wave.&rdquo Tsunamis are generated by energetic events affecting the sea floor, such as earthquakes, submarine landslides , and volcanic eruptions (see Chapter 9 and Chapter 4). During earthquakes for example, tsunamis can be produced when the moving crustal rocks below the sea abruptly elevate a portion of the seafloor. Water is suddenly lifted creating a bulge at the surface and a wave train spreads out in all directions traveling at tremendous speeds [over 322 kph (200 mph)] and carrying enormous energy. Tsunamis may pass unnoticed in the open ocean because they move so fast, the wavelength is very long, and the wave height is very low. But, as the wave train approaches shore and each wave begins to interact with the shallow seafloor, friction increases and the wave slows down. Still carrying its enormous energy, wave height builds up and the wave strikes the shore as a wall of water that can be over 30 m (

100 ft) high. The massive wave, called a tsunami runup, may sweep inland well beyond the beach destroying structures far inland. Tsunamis can deliver a catastrophic blow to people at the beach. As the trough water in front of the tsunami wave is drawn back, the seafloor is exposed. Curious and unsuspecting people on the beach may run out to see exposed offshore sea life only to be overwhelmed when the breaking crest hits.

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Chapter 12 Geological Structures

After carefully reading this chapter, completing the exercises within it, and answering the questions at the end, you should be able to:

  • Describe the types of stresses that exist within the Earth’s crust.
  • Explain how rocks respond to those stresses by brittle, elastic, or plastic deformation, or by fracturing.
  • Summarize how rocks become folded and know the terms used to describe the features of folds.
  • Describe the conditions under which rocks fracture.
  • Summarize the different types of faults, including normal, reverse, thrust, and strike-slip.
  • Measure the strike and dip of a geological feature.
  • Plot strike and dip information on a map.
Figure 12.0.1 A fold in sedimentary rocks near Golden and the Kickinghorse River, B.C. The coin in the middle is 26 mm across.

Observing and understanding geological structures helps us to determine the kinds of stresses that have existed within Earth’s crust in the past. This type of information is critical to our understanding of plate tectonics, earthquakes, the formation of mountains, metamorphism, and Earth resources. Some of the types of geological structures that are important to study include bedding planes, planes of foliation, dykes and sills, fractures, faults, and folds. Structural geologists make careful observations of the orientations of these structures and the amount and direction of offset along faults.


12.1 Stress and Strain

Rocks are subject to stress —mostly related to plate tectonics but also to the weight of overlying rocks—and their response to that stress is strain (deformation). In regions close to where plates are converging stress is typically compressive—the rocks are being squeezed. Where plates are diverging the stress is extensive—rocks are being pulled apart. At transform plate boundaries, where plates are moving side by side there is sideways or shear stress —meaning that there are forces in opposite directions parallel to a plane. Rocks have highly varying strain responses to stress because of their different compositions and physical properties, and because temperature is a big factor and rock temperatures within the crust can vary greatly.

We can describe the stress applied to a rock by breaking it down into three dimensions—all at right angles to one-another (Figure 12.1.1). If the rock is subject only to the pressure of burial, the stresses in all three directions will likely be the same. If it is subject to both burial and tectonic forces, the pressures will be different in different directions.

Figure 12.1.1 Depiction of the stress applied to rocks within the crust. The stress can be broken down into three components. Assuming that we’re looking down in this case, the green arrows represent north-south stress, the red arrows represent east-west stress, and the blue arrows (the one underneath is not visible) represent up-down stress. On the left, all of the stress components are the same. On the right, the north-south stress is least and the up-down stress is greatest. Figure 12.1.2 The varying types of response of geological materials to stress. The straight dashed parts are elastic strain and the curved parts are plastic strain. In each case the X marks where the material fractures. A, the strongest material, deforms relatively little and breaks at a high stress level. B, strong but brittle, shows no plastic deformation and breaks after relatively little elastic deformation. C, the most deformable, breaks only after significant elastic and plastic strain. The three deformation diagrams on the right show A and C before breaking and B after breaking.

Rock can respond to stress in three ways: it can deform elastically, it can deform plastically, and it can break or fracture. Elastic strain is reversible if the stress is removed, the rock will return to its original shape just like a rubber band that is stretched and released. Plastic strain is not reversible. As already noted, different rocks at different temperatures will behave in different ways to stress. Higher temperatures lead to more plastic behaviour. Some rocks or sediments are also more plastic when they are wet. Another factor is the rate at which the stress is applied. If the stress is applied quickly (for example, because of an extraterrestrial impact or an earthquake), there will be an increased tendency for the rock to fracture. Some different types of strain response are illustrated in Figure 12.1.2.

The outcomes of placing rock under stress are highly variable, but they include fracturing, tilting and folding, stretching and squeezing, and faulting. A fracture is a simple break that does not involve significant movement of the rock on either side. Fracturing is particularly common in volcanic rock, which shrinks as it cools. The basalt columns in Figure 12.1.3a are a good example of fracture. Beds are sometimes tilted by tectonic forces, as shown in Figure 12.1.3b, or folded as shown in Figure 12.0.1.

Figure 12.1.3 Rock structures caused by various types of strain within rocks that have been stressed. (A) Fracturing in basalt near to Whistler, BC (B) Tilting of sedimentary rock near to Exshaw, Alberta (C) Stretching of limestone at Quadra Island, BC. The light grey rock is limestone and the dark rock is chert. The body of rock has been stretched parallel to bedding. The chert, which is not elastic, has broken into fragments which are called boudins (D) Faulting within shale beds at McAbee, near to Cache Creek, BC. The fault runs from the lower right to the upper left, and the upper rock body has been pushed up and to the left.

When a body of rock is compressed in one direction it is typically extended (or stretched) in another. This is an important concept because some geological structures only form under compression, while others only form under tension. Most of the rock in Figure 12.1.3c is limestone, which is relatively easily deformed when heated. The dark rock is chert, which remains brittle. As the limestone stretched (parallel to the hammer handle) the brittle chert was forced to break into fragments to accommodate the change in shape of the body of rock. A fault is a rock boundary along which the rocks on either side have been displaced relative to each other (Figure 12.1.3d).


Table of Contents

Preface
Introduction
Co-operation of geologists with engineers
Chapter 1. Geological Investigations
1.1. Reconnaissance investigation
1.2. Detailed geological investigation
1.3. Geological investigation during construction
Chapter 2. Geological Maps and Sections
2.1. Types of geological maps
2.2. Engineering geological maps
2.3. Maps of geologically hazardous zones
2.4. Topographic base maps for geological mapping
2.5. Use of aerial photographs for geological mapping
2.6. Geological sections
Chapter 3. Mechanical Properties of Rocks
3.1. Physical background of the mechanical behavior of rocks
3.2. Character of the planes of discontinuity and methods of representation
3.3. Physical and index properties of rocks
3.4. Deformation properties of rocks
3.5. Strength of rocks
3.6. Natural stress state in rocks
3.7. Statical solutions in engineering geology
3.8. Classification of rocks
Chapter 4. Subsurface Exploration
4.1. Test pits and trenches
4.2. Exploratory drifts
4.3. Sounding
4.4. Boreholes
4.5. Evaluation of subsurface exploration
4.6. Construction of geological sections from bore logs
4.7. Plan and lay-out of subsurface exploration
Chapter 5. Geophysical Methods
5.1. Geophysical methods used in the geological investigation of a site
5.2. Determination of rock properties
5.3. Geophysical methods used in hydrogeological research
Chapter 6. Weathering of Rocks
6.1. Physical weathering
6.2. Products of Pleistocene physical weathering
6.3. Chemical weathering
6.4. Investigation of the weathered zone
Chapter 7. Slope Movements, Landslides
7.1. Economic significance of slope movements
7.2. Factors producing earth movements
7.3. Division of slope movements
7.4. Slope movements of surface deposits
7.5. Landslides in clayey rocks
7.6. Sliding movements of solid rocks
7.7. Specific types of slope movements
7.8. Stabilization of slopes in slide areas
Chapter 8. Excavation and Workability of Rocks
8.1. Resistance of rock to excavation
8.2. Drillability of rocks
8.3. Workability of rocks
8.4. Bulking (increase in volume) of rocks
Chapter 9. Geological Investigation of Building Material Deposits
9.1. Reconnaissance of a deposit
9.2. The aim of detailed engineering geological investigation
9.3. Basic principles of quarry opening
9.4. Deposits of sand and gravel
9.5. Working of building material and protection of the environment
Chapter 10. Foundation of Buildings and Industrial Structures
10.1. Demands made on the foundation of structures
10.2. Mechanical behavior of foundation soils
10.3. Foundation and ground water
10.4. Foundation excavation
10.5. Choice of foundation method
10.6. Investigation of the building site
10.7. Evaluation of the site
10.8. Foundation conditions related to the regional geology
10.9. Measurement of deformations of structures
Chapter 11. Roads and Railways
11.1. Geological requirements on the design of transportation routes
11.2. Preliminary investigation for the general location of the route
11.3. Detailed investigation for route location
11.4. Cuttings and half-cuttings
11.5. Embankments
11.6. Roadways and their subgrades
11.7. Geological investigation for bridges and other structures
11.8. Activity of the engineering geologist during construction and maintenance
Chapter 12. Tunnels and Underground Power Plants
12.1. Introduction
12.2. Tasks of engineering geological research
12.3. Investigation of the geology of the area and general alignment of the tunnel
12.4. The hydrogeological conditions
12.5. Detailed investigation for the location of the tunnel
12.6. Mechanical behavior of rock and pressure on tunnel lining
12.7. Tunneling methods
12.8. Rock temperature and ventilation
12.9. Hydraulic tunnels
12.10. Underground railway tunnels
Chapter 13. Engineering-geological Investigations for Hydraulic Structures
13.1. Reconnaissance investigation
13.2. Detailed geological investigation
13.3. Co-operation of engineering geologist during construction
13.4. Investigation of the damsite
13.5. Geomorphological and geological setting of the damsite
13.6. Damsites in igneous and metamorphic rocks
13.7. Damsites on sedimentary rocks
13.8. Foundation of gravity dams
13.9. Foundation of arch dams
13.10. Geological investigations for earth dams
13.11. Water-pressure tests and test grouting
13.12. Investigation of the reservoir area
13.13. Watertightness of the reservoir
13.14. Stability of reservoir banks
13.15. Siltation of reservoirs
13.16. Economic effects of impounding water
13.17. Discharge of water from the reservoir
13.18. Engineering-geological investigation of sites for power plants
Chapter 14. Tasks of Geological Investigation in Regional Planning and Environmental Policy
14.1. Man as a geological agent
14.2. Regional planning
14.3. Geological analysis
14.4. Hydrogeological analysis
14.5. Geological investigation in planning and building of settlements
Bibliography
Index


Earth, Atmospheric, and Planetary Sciences (Course 12)

General Institute Requirements (GIRs)

The General Institute Requirements include a Communication Requirement that is integrated into both the HASS Requirement and the requirements of each major see details below.

Summary of Subject Requirements Subjects
Science Requirement 6
Humanities, Arts, and Social Sciences (HASS) Requirement at least two of these subjects must be designated as communication-intensive (CI-H) to fulfill the Communication Requirement. 8
Restricted Electives in Science and Technology (REST) Requirement [can be satisfied by 12.001, 12.002, or 12.003, and 18.03 in the Departmental Program] 2
Laboratory Requirement (12 units) [can be satisfied by a laboratory/field subject in the Departmental Program] 1
Total GIR Subjects Required for SB Degree 17
Physical Education Requirement
Swimming requirement, plus four physical education courses for eight points.

Departmental Program

Choose at least two subjects in the major that are designated as communication-intensive (CI-M) to fulfill the Communication Requirement.

The units for any subject that counts as one of the 17 GIR subjects cannot also be counted as units required beyond the GIRs.

With approval of the advisor, one subject may be counted toward concentration coursework if not taken as a General Departmental Requirement.

Recommended for concentration area 1. May also be applicable to areas 3 and 4.

Recommended for concentration areas 2 and 4.

Recommended for concentration area 3.

Areas of Concentration 1

Area 1—Geoscience: Geology, Geochemistry, Geophysics, Geobiology 2
Select 60-63 units:
12.005Applications of Continuum Mechanics to Earth, Atmospheric, and Planetary Sciences12
12.104Geochemistry of Natural Waters12
12.108Structure of Earth Materials12
12.109Petrology15
12.110ASedimentary Environments6
12.110BSedimentology in the Field9
12.113Structural Geology12
12.117AField Geobiology I6
12.117BField Geobiology II9
12.163Geomorphology12
12.177Astrobiology, Origins and Early Evolution of Life12
12.178The Phylogenomic Planetary Record12
12.201Essentials of Global Geophysics12
12.214Essentials of Applied Geophysics12
12.421Physical Principles of Remote Sensing12
Area 2—Atmospheres, Oceans, and Climate 3
12.301Climate Science12
or 12.318 Introduction to Atmospheric Data and Large-scale Dynamics
Select 48 units:
12.009[J]Nonlinear Dynamics: The Natural Environment12
12.086Modeling Environmental Complexity12
12.300[J]Global Change Science12
12.306Atmospheric Physics and Chemistry12
12.315Atmospheric Radiation and Convection12
12.320A[J]Introduction to Hydrology and Water Resources6
12.320B[J]Introduction to Hydrology Modeling6
12.336[J]Air Pollution and Atmospheric Chemistry12
12.338Aerosol and Cloud Microphysics and Chemistry12
12.349Mechanisms and Models of the Global Carbon Cycle12
12.372Elements of Modern Oceanography12
12.373Field Oceanography15
12.377The History of Earth's Climate12
12.390Fluid Dynamics of the Atmosphere and Ocean12
12.421Physical Principles of Remote Sensing12
12.422Planetary Atmospheres12
Area 3—Planetary Science and Astronomy 4
12.420Essentials of Planetary Science12
Select 48-51 units:
12.006[J]Nonlinear Dynamics: Chaos12
12.104Geochemistry of Natural Waters12
12.108Structure of Earth Materials12
12.109Petrology15
12.177Astrobiology, Origins and Early Evolution of Life12
12.421Physical Principles of Remote Sensing12
12.422Planetary Atmospheres12
12.425[J]Extrasolar Planets: Physics and Detection Techniques12
12.43[J]Space Systems Engineering12
Area 4—Environmental Systems 5
Select 60-63 units:
12.009[J]Nonlinear Dynamics: The Natural Environment12
12.021Earth Science, Energy, and the Environment12
12.031[J]Fundamentals of Ecology12
12.086Modeling Environmental Complexity12
12.110ASedimentary Environments6
12.110BSedimentology in the Field9
12.117AField Geobiology I6
12.117BField Geobiology II9
12.119Harnessing Power from Environmental Microbes and Chemical Gradients9
12.158Molecular Biogeochemistry9
12.163Geomorphology12
12.174Chemistry of Life3
12.177Astrobiology, Origins and Early Evolution of Life12
12.301Climate Science12
12.346[J]Global Environmental Negotiations6
12.348[J]Global Climate Change: Economics, Science, and Policy9
12.349Mechanisms and Models of the Global Carbon Cycle12
12.377The History of Earth's Climate12
12.385Science, Politics, and Environmental Policy9
12.421Physical Principles of Remote Sensing12
1

With approval of the academic advisor, students may count one subject from list of General Department Requirements as long as it is also not counting toward the General Department Requirement. Students may also substitute one subject from off of the degree chart if approved by the academic advisor.

Recommended supporting subjects: 3.012 or 5.60 , 5.12 , 7.05 , 18.03 or 18.06 .

Recommended supporting subjects: 5.60 , 8.03 , 18.03 .

Recommended supporting subjects: 8.03 , 8.04 , 8.044 , 18.03 .

Recommended supporting subjects: 5.12 , 6.802[J] , 8.03 , 18.03 or 18.06 .


12.1: Introduction - Geosciences

Rocks are subject to stress —mostly related to plate tectonics but also to the weight of overlying rocks—and their response to that stress is strain (deformation). In regions close to where plates are converging stress is typically compressive—the rocks are being squeezed. Where plates are diverging the stress is extensive—rocks are being pulled apart. At transform plate boundaries, where plates are moving side by side there is sideways or shear stress—meaning that there are forces in opposite directions parallel to a plane. Rocks have highly varying strain responses to stress because of their different compositions and physical properties, and because temperature is a big factor and rock temperatures within the crust can vary greatly.

We can describe the stress applied to a rock by breaking it down into three dimensions—all at right angles to one-another (Figure 12.2). If the rock is subject only to the pressure of burial, the stresses in all three directions will likely be the same. If it is subject to both burial and tectonic forces, the pressures will be different in different directions.

Figure 12.2 Depiction of the stress applied to rocks within the crust. The stress can be broken down into three components. Assuming that we’re looking down in this case, the green arrows represent north-south stress, the red arrows represent east-west stress, and the blue arrows (the one underneath is not visible) represent up-down stress. On the left, all of the stress components are the same. On the right, the north-south stress is least and the up-down stress is greatest. [SE]

Rock can respond to stress in three ways: it can deform elastically, it can deform plastically, and it can break or fracture. Elastic strain is reversible if the stress is removed, the rock will return to its original shape just like a rubber band that is stretched and released. Plastic strain is not reversible. As already noted, different rocks at different temperatures will behave in different ways to stress. Higher temperatures lead to more plastic behavior. Some rocks or sediments are also more plastic when they are wet. Another factor is the rate at which the stress is applied. If the stress is applied quickly (for example, because of an extraterrestrial impact or an earthquake), there will be an increased tendency for the rock to fracture. Some different types of strain response are illustrated in Figure 12.3.

Figure 12.3 The varying types of response of geological materials to stress. The straight dashed parts are elastic strain and the curved parts are plastic strain. In each case the X marks where the material fractures. A, the strongest material, deforms relatively little and breaks at a high stress level. B, strong but brittle, shows no plastic deformation and breaks after relatively little elastic deformation. C, the most deformable, breaks only after significant elastic and plastic strain. The three deformation diagrams on the right show A and C before breaking and B after breaking. [SE]

The outcomes of placing rock under stress are highly variable, but they include fracturing, tilting and folding, stretching and squeezing, and faulting. A fracture is a simple break that does not involve significant movement of the rock on either side. Fracturing is particularly common in volcanic rock, which shrinks as it cools. The basalt columns in Figure 12.4a are a good example of fracture. Beds are sometimes tilted by tectonic forces, as shown in Figure 12.4b, or folded as shown in Figure 12.1.

Figure 12.4 Rock structures caused by various types of strain within rocks that have been stressed [all by SE]

When a body of rock is compressed in one direction it is typically extended (or stretched) in another. This is an important concept because some geological structures only form under compression, while others only form under tension. Most of the rock in Figure 12.4c is limestone, which is relatively easily deformed when heated. The dark rock is chert, which remains brittle. As the limestone stretched (parallel to the hammer handle) the brittle chert was forced to break into fragments to accommodate the change in shape of the body of rock. A fault is a rock boundary along which the rocks on either side have been displaced relative to each other (Figure 12.4d).


1. Introduction

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2009-2010 Undergraduate Course Catalog & Academic Policies

www.geos.vt.edu/
E-mail: [email protected]

K. A. Eriksson, Chair
J. A. Spotila, Associate Chair

University Distinguished Professor: R.J. Bodnar M.F. Hochella, Jr.
Professors: R.J. Bodnar P.M. Dove K.A. Eriksson M.F. Hochella, Jr.
S.D. King M.J. Kowalewski R.D. Law J. F. Read J.D. Rimstidt N.L. Ross R.J. Tracy, S. Xiao
Associate Professors: T.J. Burbey J.A. Hole M. E. Schreiber J.A. Spotila
C.J. Weiss
Assistant Professors: B.M. Bekken Y. Zhou
Research Professors: R.J. Angel R.P. Lowell
Research Assistant Professor: M.C. Chapman
Adjunct and Affiliated Faculty: J. Beard J Chermak B. DeVivo A. Dooley
N. Fraser W. Henika J. Hunter R. Koepnick M. Mikulich C. Szabo L. Ward C. Watts

Overview

Geosciences offer exciting opportunities for students with an interest in applying a full range of science and mathematical skills to understand the earth’s properties and dynamic processes. This is a highly interdisciplinary program that applies physics, chemistry, biology, and mathematics to understand and manage all aspects of Earth and the environment. Geoscientists work everywhere in the world under almost any condition as they search for earth resources, manage the environment and natural hazards, and supervise technical and business enterprises. For more information about exciting careers in Geosciences consult earthinspace.org/careers/, www.agiweb.org/careers.html, and www.bls.gov/oco/ocos050.htm. The extensive scientific and mathematical skills of geoscientists, along with their broad field experience, allow them to pursue careers in many related fields ranging from material science to technical management to scientific reporting.

The internationally recognized faculty in Geosciences has developed four challenging options, described below, that lead to a B.S. in Geosciences. Coursework emphasizes the acquisition and processing of field data beginning with a special course in field methods taken in the spring of the first year. The geology option requires, and the other options recommend, that the student participate in a six-week field camp. The B.S. in Geosciences provides pre-professional preparation that will allow students to continue their education in post graduate programs in science, law, and business.

Earth systems and processes are enormously complicated and require a full range of intellectual skills to decipher and manage. Geoscientists must possess good quantitative skills and a solid understanding of physics, chemistry, and biology. They must be able to read maps, identify rocks, minerals, and fossils as well as visualize earth structures in three dimensions. They must have strong communication skills, both written and verbal. Learning to use these skills in an integrated way is a challenging and rewarding experience.

Geology Option

The Geology option offers a detailed coverage of the broad range of classic disciplines within the geosciences. This option emphasized the study of minerals, rocks and fossils, and teaches the student how to understand the processes and history of the earth based on the occurrences and relationships of these materials at or near the Earth's surface. The required curriculum for undergraduates pursuing the B.S. in Geosciences with a option in Geology are BIOL 1105, 1106, 1115, 1116 (8C) CHEM 1035, 1036, 1045, 1046 (8C) GEOS 1004, 1005, 1014, 1104, 2444, 3104, 3204, 3404, 3504, 3604, 3704, 4024, 4494, 4000 level courses (50C) MATH 1114, 1205, 1206, 1224, 2224 (13C) PHYS 2305, 2306 (8C) STAT 3005 (3C) free electives (6C).

Geochemistry Option

The Geochemistry option is designed for those students who have special interest in the chemical aspects of the Earth and its materials. The required curriculum for undergraduates pursuing the B.S. in Geosciences with an option in Geochemistry are: CHEM 1035, 1036, 1045, 1046, plus 10 additional credits selected from 2114, 2124, 2514, 2535, 2536, 2545, 2546, 3114, 3124, 3615, 3625, 4615, 4616, or 4424 (18C) GEOS 1004, 1005, 1014, 1024, 1104, 1124, 2444, 3104, 3204, 3404, 3504, 3604, 3704, 4024, 4634, 4974 (43C) MATH 1114, 1205, 1206, 1224, 2214, 2224 (16C) PHYS 2305, 2306 (8C) STAT 3005 (3C) 3-4000 level additional courses from the Departments of Biochemistry, Biological Sciences, Chemical Engineering, Chemistry, Civil and Environmental Engineering, Computer Science, Crop and Soil Environmental Sciences, Engineering Science and Mechanics, Geosciences, Materials Science and Engineering, Mathematics, Mining and Minerals Engineering, Physics, or Statistics (7C) free electives (4C).

Geophysics Option

The Geophysics option offers the student the opportunity to specialize in the branch of the geosciences that investigates physical earth processes such as earthquakes and that images the interior of the earth through surface-based physical measurements. The required courses for the B.S. in Geosciences with an option in Geophysics are: CHEM 1035, 1036, 1045, 1046 (8C) CS 1044 (3C) GEOS 1004, 1005, 1014, 1104, 2444, 3104, 3204, 3404, 3504, 3604, 3704, 4024, 4124, 4154, 4164, 4174, (46C) MATH 1114, 1205, 1206, 1224, 2214, 2224 (16C) PHYS 2305, 2306 (8C) Science/Math courses (6C) STAT 3005 (3C) free electives (6C).

Earth Science Education Option

The Earth Science education option provides students with a broad earth science curriculum that meets the content goals for secondary earth science teaching. Certification for Earth science teaching is not provided in the program. Information about teaching certification in Virginia can be obtained from the Department of Teaching and Learning. The courses required to complete a B.S. in Geosciences with an option in Earth Science Education are: BIOL 1105, 1106, 1115, 1116 (8C) CHEM 1035, 1036, 1045, 1046, 2514 (11C) GEOS 1004, 1005, 1014, 1024, 1104, 1124, 2444, 3034, 3104, 3114, 3204, 3404, 3504, 3604, 3704, 4024, 3-4000 courses (48C) MATH 1114, 1205, 1206, 1224 (10C) PHYS 1055, 1115, 2305, 2306 (12C) STAT 3005 (3C) free electives (7C).

Minor in Geosciences

Requirements include GEOS 1004, 1014, 1104 (8C) plus 3-4000 level courses in geosciences (12C). GEOS 2104 duplicates GEOS 1004 for 3 credits only. GEOS 4974 and 4994 may not be used toward the minimum of 20 total credits

Graduate Program

The department offers M.S. and Ph.D. degrees in geosciences with specializations in many sub-disciplines. (See the Graduate Catalog for further information.)

Satisfactory Progress

University policy requires that students who are making satisfactory progress toward a degree meet minimum criteria toward the Curriculum for Liberal Education (see Academics chapter in this catalog), toward the College of Science Core (see first part of this chapter) and toward the degree in geosciences.

Satisfactory progress toward the B.S. in Geosciences, Geology option, requires that:

  • Satisfactory progress toward the B.S. in Geosciences, Earth Science Education option, requires that:

Undergraduate Courses (GEOS)

1004: PHYSICAL GEOLOGY
Minerals and rocks, internal and external processes especially the modification of landscape, global plate tectonics, and their interrelationships introduction to the more direct aspects of human interactions with the natural physical environment. (3H,3C)

1005-1006: GEOSCIENCE FUNDAMENTALS
Introduction to professional expectations and career options for students pursuing a degree in Geosciences. 1005: Scientific methodology, empirical reasoning, and the specific application of these methods to the Geosciences. Introduction to accessing and using geoscientific resources, computer graphics and database applications in geoscience, and methods of oral and written technical communication. 1006: Career opportunities in geoscience, introduction to research, GIS applications in geoscience, case studies of applied geoscience.
Co: 1004 for 1005 1014 for 1006. (3L,1C)

1014: THE EARTH AND LIFE THROUGH TIME
Scientific examination of rocks, fossils, and the earth's interior as clues to global-scale geological and biological processes that have shaped our planet and its biosphere through time. Origin and physical evolution of the earth, oceans, and atmosphere origin and evolution of life plate tectonics and mountain-building events global climate changes major evolutionary innovations mass extinction events. (3H,3L,4C)

1024: RESOURCES GEOLOGY AND THE ENVIRONMENT
The nature, origin, occurrence, distribution, use, and limitations of the earth's mineral resources including abundant and scarce metals, precious metals and gems, building materials, industrial minerals, fossil fuels, nuclear energy, water, soils, and other minerals. (3H,3C)

1104: PHYSICAL GEOLOGY LABORATORY
Identification of minerals and rocks topographic maps and air photographs and their use in understanding landscape and geologic influences on human activities geologic maps. (3L,1C)

1124: RESOURCES GEOLOGY AND THE ENVIRONMENT LABORATORY
Laboratory exercises dealing with the nature of mineral resources, how they are exploited, and the practical concerns associated with their extraction. (3L,1C)

2014: MISSION TO THE PLANETS
The physical, chemical, and geological nature of the terrestrial planets and their atmospheres similarities and differences between the Earth and other terrestrial planets manned and unmanned space probes and how they have shaped our understanding of the planets. (3H,3C)

2104: ELEMENTS OF GEOLOGY
Structure of the earth, properties of minerals and rocks, and geologic processes that act on the surface and in the interior of the earth, and integrated geologic systems of importance in engineering and regional planning. For students in engineering and physical sciences. Geology 2104 duplicates material in Geology 1004 and both may not be taken for credit. (2H,3L,3C)

2444: GEOSCIENCE FIELD OBSERVATIONS
Study of geological phenomena in the field. Students make observations in the field, integrate them into coherent datasets, and construct interpretations. Rock type and structure identification in outcrop. Field techniques and applications in structural geology, sedimentology, stratigraphy, geomorphology, environmental geology, hydrogeology, geochemistry, and geophysics. 10 full days spent in the field (Mondays through Fridays during Summer I), plus additional classroom or laboratory meetings. Pre: 1004, 1014, 1104. (6L,2C)

2964: FIELD STUDY
Pass/Fail only. Variable credit course. X-grade allowed.

2974: INDEPENDENT STUDY
Variable credit course.

2984: SPECIAL STUDY
Variable credit course. X-grade allowed.

3014: ENVIRONMENTAL GEOSCIENCES
The roles of geology and geophysics in defining and monitoring the natural environment, with special application to interactions between humans and the geologic environment. Both descriptive treatment and quantitative concepts related to environmental processes involving the solid earth and earth's surface, with emphasis on geologic hazards (e.g., earthquakes, volcanoes, landslides and slope failures, flooding, groundwater problems, mineral and rock dusts). Pre: 1004 or 1024 or 2104. (3H,3C)

3024: FORTRAN FOR PHYSICAL SCIENCE
Computer programming using Fortran 95 with applications to physical science, including statistics, physics, geology, and hydrology. Applications used to expose students to the capabilities of the language will include arrays, I/O concepts, structured programming, data types, procedures and modules, and dynamic data structures. Pre: MATH 1114, MATH 1206 or MATH 2015. (3H,3C)

3034: OCEANOGRAPHY
Descriptive and quantitative treatment of the geological, physical, chemical and biological processes that occur in, or are influenced by, the oceans. The history of oceanic exploration and discovery is addressed. Pre: MATH 1206 or MATH 2015. (3H,3C)

3104: ELEMENTARY GEOPHYSICS
Acquisition and interpretation of exploration geophysical data. Seismic reflection and refraction methods, gravity and magnetic fields, geoelectrical methods, and geophysical well logging. Pre: MATH 1205. (2H,3L,3C)

3114 (GEOG 3114): INTRODUCTION TO METEOROLOGY
A nonmathematical introduction to meteorology including consideration of the structure of the atmosphere, energy balance in the atmosphere, clouds and precipitation, air masses and fronts, global circulation, storms, climatology, catastrophic weather, meteorological optics, and forecasting. (2H,3L,3C)

3204: SEDIMENTOLOGY-STRATIGRAPHY
Study of sedimentary basins in a plate-tectonic framework, mechanisms of basin formation, three-dimensional geometry of basin fill, and controls on basin fill. Siliciclastic and carbonate-evaporate rocks as examples of basin fill are discussed in lectures and studied in the lab and in the field. Applied aspects of the course include a discussion of geometries of sedimentary aquifers and reservoirs. Pre: 1004 or 1014. (2H,3L,3C)

3304 (CSES 3304) (GEOG 3304): GEOMORPHOLOGY
Examines the variety of landforms that exist at the earth's surface. Detailed investigation of major processes operating at the earth's surface including: tectonic, weathering, fluvial, coastal, eolian, and glacial processes. Field excursion. Pre: GEOG 1104 or GEOS 1004 or GEOS 2104. (3H,3C)

3404: ELEMENTS OF STRUCTURAL GEOLOGY
Introduction to basic geological structures, evolution of microfabrics, development of faults, folds and foliations, stereographic analysis of geological structures, thrust fault geometries, balancing of geological cross-sections, and introduction to the concepts of stress and strain. Pre: 1004. (2H,3L,3C)

3504 (MSE 3104): MINERALOGY
Principles of modern mineralogy, crystal chemistry, and crystallography, with emphasis on mineral atomic structure and physical property relationships, mineralogy in the context of geology, geochemistry, environmental science and geophysics, phase equilibria, mineral associations, and mineral identification, and industrial applications of minerals. There are three required field trips during the semester. Pre: MATH 1205, CHEM 1036. (2H,3L,3C)

3524 (MSE 3124): OPTICAL MINERALOGY
Principles of color and the behavior of light in crystalline materials use of the petrographic microscope in the identification of minerals using optical techniques. Pre: 1004. Co: 3504. (3L,1C)

3604: PALEONTOLOGY
Paleontological principles and techniques and their application to the evolution of life, the ecological structure of ancient biological communities, the interpretation of ancient depositional environments, and the history of the earth. Pre: 1004, 1014. (2H,3L,3C)

3614 (CSES 3114) (ENSC 3114): SOILS
Characterization of soils as a natural resource emphasizing their physical, chemical, mineralogical, and biological properties in relation to nutrient availability, fertilization, plant growth, land-use management, waste application, soil and water quality, and food production. For CSES, ENSC, and related plant- and earth-science majors. Partially duplicates CSES/ENSC 3134. Pre: CHEM 1036. (3H,3C)

3624 (CSES 3124) (ENSC 3124): SOILS LABORATORY
Parent materials, morphology, physical, chemical, and biological properties of soils and related soil management and land use practices will be studied in field and lab. Partially duplicates CSES/ENSC 3134. Co: 3614. (3L,1C)

3704: IGNEOUS AND METAMORPHIC ROCKS
Study of characteristics and mechanisms of igneous intrusion at depth in the crust, volcanic phenomena on the surface, and textural and mineralogical modification of rocks at elevated temperatures and pressures of crustal metamorphism. Tectonic aspects of igneous and metamorphic rocks will be stressed. Pre: 1004, 1014. Co: 3504. (2H,3L,3C)

4024: SENIOR SEMINAR
Investigation and solution of significant geologic research problems by analysis and integration of information across a wide spectrum of Geosciences subdisciplines, and the presentation of results in oral and written form. Research projects will provide maximum student exposure to the full breadth of the Geosciences and the interrelated nature of subdisciplines. Pre: 3104, 3204, 3404, 3504, 3604, 3704. (3H,3C)

4084 (GEOG 4084): INTRODUCTION TO GIS
Use of automated systems for geographic data collection, digitization, storage, display and analysis. Basic data flow in GIS applications. Overview of GIS applications. Group homework projects to develop proficiency in the use of current GIS software. Prior experience with personal computers recommended. (3H,3C)

4124: SEISMIC STRATIGRAPHY
Overview of seismic data acquisition and processing methods, seismic wavelets, static and dynamic corrections, and seismic velocities seismic reflection data interpretation seismic reflection responses Seismic mapping seismic stratigraphy and seismic lithology. Consent required. Pre: 3104. (2H,3L,3C)

4154: EARTHQUAKE SEISMOLOGY
Seismicity and its causes in the context of plate tectonics determination of earthquake location, size and focal parameters seismogram interpretation seismometry hazard potential use of earthquakes in determining earth structure. Pre: MATH 2214, MATH 2224, PHYS 2305, GEOS 3104. (2H,3L,3C)

4164: POTENTIAL FIELD METHODS IN EXPLORATION GEOPHYSICS
Theory and application to engineering, environmental, and resource exploration. Gravity, magnetics, electrical resistivity, self potential, induced polarization, ground-penetrating radar, magnetotellurics, electromagnetic induction. Pre: 3104, MATH 2214, MATH 2224, PHYS 2306. (3H,3L,4C)

4174: EXPLORATION SEISMOLOGY
Theory and application of seismic methods to engineering, environmental and resource exploration: reflection seismics, refraction seismics, and tomography. Data acquisition, digital filtering, data corrections, imaging, interpretation, and forward modeling. Pre: 3104, MATH 2224, PHYS 2305, PHYS 2306. (3H,3L,4C)

4324 (BIOL 4324): PLANT EVOLUTION (WRITING INTENSIVE)
Geological history, comparative morphology, evolution and systematics of pre-vascular and vascular plants. Focus on evolution of communities, adaptive construction of tissues and organs, and ecology of reproduction. Pre: BIOL 2304. (2H,6L,4C)

4354 (GEOG 4354): INTRODUCTION TO REMOTE SENSING
Theory and methods of remote sensing. Practical exercises in interpretation of aerial photography, satellite, radar and thermal infrared imagery. Digital analysis, image classification and evaluation. Applications in earth sciences, hydrology, plant sciences, and land use studies. (2H,3L,3C)

4404: ADVANCED STRUCTURAL GEOLOGY
Basic principles of rock behavior under applied, non-hydrostatic stress (experimental and tectonic) and analysis of the geometrical patterns produced. Alternate years. Pre: 3404. (2H,3L,3C)

4414: ENGINEERING GEOLOGY
The geological principles and techniques that are required in civil engineering projects and the influence of geology on design, location, construction, and stability of engineering structures. Pre: 1004 or 2104. (2H,2C)

4494: GEOLOGY SUMMER FIELD COURSE
Synthesis of course work through field mapping and studies of topical areas in soft- and hard-rock terrains. Geology of the southern Appalachian Blue Ridge and Valley and Ridge Provinces. Training in field methods and techniques. Consent required. Pre: 1004, 1014, 3404. (2H,48L,6C)

4554: GEOLOGIC ASPECTS OF NUCLEAR AND TOXIC WASTE DISPOSAL
Review of the geochemical characteristics of radionuclides and other toxic, inorganic materials and how these characteristics affect safe disposal of these materials in the natural environment. Examination of the effects of near-surface geologic processes such as groundwater movement and geologic hazards on long-term storage of nuclear wastes, with application to evaluation of current and proposed disposal sites. Pre: CHEM 1036. (2H,3L,3C)

4624: MINERAL DEPOSITS
Introduction to the range and variety of metallic and non-metallic economic mineral deposits. Classification of the petrologic and tectonic settings of mineral deposits. Source, transport and depositional mechanisms of mineral deposit formation. Laboratory emphasizes identification of ore minerals, gangue minerals, common host rocks, wall-rock alteration and mineral zoning. Pre: (1004 or 2104), (3104 or 3404). (2H,3L,3C)

4634: ENVIRONMENTAL GEOCHEMISTRY
Application of quantitative methods of thermodynamic and physicochemical analysis to the study of the distribution and movement of chemical elements in surface and near-surface geological environments. Emphasis on practical approaches to environmental geochemistry. Pre: MATH 1205, CHEM 1036. (2H,3L,3C)

4644: ORGANIC GEOCHEMISTRY
Composition, origin and distribution of organic matter in the geological environment the carbon cycle terminology and structure of organic molecules metamorphism of organic materials formation and composition of coal, oil, natural gas organic geochemistry of the oceans role of organics in ore formation organic compounds in natural waters abiogenic organic compounds in magmatic rocks and fluids. Pre: 1004 or 2104, 1014 or 1024, CHEM 1036. (3H,3C)

4714: VOLCANOES AND VOLCANIC PROCESSES
Study of characteristics and mechanisms of volcanic phenomena, including magma dynamics, origin and chemistry of lavas, physics of eruptions, and characteristics of volcanic products, particularly pyroclastic deposits. Includes focus on volcanism as a general planetary process, on terrestrial tectonic settings of volcanism and on volcanic hazards. Pre: 3704. (2H,3L,3C)

4804: GROUNDWATER HYDROLOGY
Physical principles of groundwater flow, including application of analytical solutions to real-world problems. Well hydraulics. Geologic controls on groundwater flow. Pre: (1014, PHYS 2205) or (PHYS 2305, MATH 1206). (2H,3L,3C)

4964: FIELD STUDY
Pass/Fail only. Variable credit course.

4974: INDEPENDENT STUDY
Variable credit course.

4984: SPECIAL STUDY
Variable credit course.

4994: UNDERGRADUATE RESEARCH
May be repeated for a maximum of 4 credits. Variable credit course.


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