Class Geology 101 Study Guide – Test #2 Chapter 5 Know how sedimentary rocks are classified based on texture (clastic rocks, Figure 5.4) and chemical composition (chemical/organic rocks). Be able to identify a sedimentary rock if given a description (i.e., if I give you grain size, you should be able to tell me the type of clastic rock). Understand how grain size relates to the energy of the depositional system. Understand transgression and regression. Given a stratigraphic sequence of sedimentary rocks, be able to determine whether that sequence is a record of transgression or regression. FIGURE 5.26 Be able to define/identify these sedimentary structures: stratification, cross bedding, graded bedding, ripple marks, mud cracks. Know how these structures relate to the depositional environment (e.g., how/where they form). FIGURE 5.2, FIGURE 5.9 Cross-bedding, Figure 5.10 Graded bedding The type of rock and its structures are important records of past depositional environments. Know the major sedimentary systems, their important characteristics and types of sediments that accumulate in them (Figures 5.13; and 5.14-5.25; are key). In other words, know how sedimentary rocks form and how their formation and structural features relate to depositional environments. Chapter 6 Know the rock cycle – this links all the various rock types to plate tectonics and surface processes. Know how metamorphic rocks form, including the processes of recrystalization, plastic deformation. Know how metamorphism occurs under pressure, temperature, and composition changes; understand where these conditions take place in relation to plate tectonics (figures 6.4 (Where), 6.6, 6.19 are a good place to start). The driving forces for metamorphism are changes in temperature, pressure, and composition of the environment or strong deformation.These changes cause recrystallization in the solid state as the rock changes toward equilibrium with the new environment. Understand stability diagrams and be able to use them to predict what mineral would be stable under given environmental conditions. Figure 6.5 Know how metamorphic rocks are classified; be able to identify the common metamorphic rocks presented in class and lab (and in the chapter). Understand why some rocks are foliated and some are not. Know figure 13. Foliation is caused by differential stress and shearing. Usually occurs during the recrystallization step. Understand figure 6.16. Be able to use information about metamorphic facies to identify metamorphic grade in relation to plate tectonics (again, figure 6.19 will help with this). Where and why… In other words, know how and under what conditions rocks are metamorphosed, what a given rock metamorphoses into for a given set of conditions (high temperature metamorphism of sandstone equals quartzite), where those conditions and their associated metamorphic rocks occur. Chapter 7 Now that we’ve created rocks in chapters 3-6, chapter 7 discusses how we modify their structure. Be able to identify the types of folds, geometries of folds, and types of faults that can occur. Be able to link the types of stress and types of deformation that give rise to these structures. Know what factors influence how a given rock body deforms in response to a given stress. Figure 7.4 Know the terminology associated with folds and faults (limb, hinge, hanging wall, etc.). Be able to identify folds and faults given a description of the dip of limbs, ages of rocks as you walk from the limb to the hinge axis, direction of movement of the hanging wall, etc. We did a large number of examples of this in class. Hanging wall, footwall, forelimb, back limb, top limb. Figure 7.11. Rule of v’s (Figure 7.15) Eroded V’s point the direction the bed dips Be able to identify a plunging fold, whether it is an anticline or syncline, and its major features (direction the “v” points, dip of the limbs, etc). Age of rock (syncline and anticline) Know the large scale features that result from regional stress – fold and thrust belts, horst and graben, shortening and thickening of the crust, etc. Be able to identify the type of plate margin given a description (or figure) of the dominant structural features. And be able to do the reverse (give the most likely structural features that would occur at a given plate boundary). In other words, be able to use the information above to relate structural features to plate tectonics. In other words, know how rocks are deformed, the processes that influence that deformation, the types of structures that result, and where those structures occur with respect to tectonic setting. Chapter 8 Know the difference and importance of both relative and absolute dating. Know the relative dating tools (principles) and unconformities. Be able to identify examples of each. Be able to use these to place a sequence of events in relative order (given a description or a cross section). (Major Concepts #2) Understand the principle of absolute dating. Know how elements radioactively decay, how this relates to half-life (and whether radioactive decay occurs linearly or exponentially), and how geologists use unstable (radioactive) isotopes to date a sample. Be able to determine the number of half-lives required to remove a given fraction of radioactive atoms (or the reverse: what fraction of radioactive atoms remain after a given number of half-lives). Figure 8.11 Know how absolute ages of crust relate to the major features of the continents. Know what evidence geologists use to determine the age of the earth. Potassium-Argon Dating Understand how the standard geologic column was first developed (the relative dating tools), and how absolute dating has improved our understanding of the time divisions within that column. FIGURE 8.8 (caption) The original order of the units in the geologic column was based on the sequence of rock formations in their superposed order as they are found in Europe. In other words, know the difference between relative and absolute dating, how we date rock sequences using both methods, and why both methods are important. Chapter 18 Understand elastic rebound and how it relates to earthquakes. Figure 1.8 Know the difference between P, S, and surface waves (in terms of motion, speed, etc.) Figure 18.3. Know the differences between the schemes used to determine the intensity(measured in relation to effects on humans)/magnitude(objective scale of energy released) of an earthquake moment magnitude is the most widely used today. Know how we use the properties and energy of the waves to locate the epicenter and focus of an earthquake (figure 18.4) Understand how the distribution of focal depths around the world relates to plate boundaries. Know how material properties affect how/whether the different seismic waves are transmitted through the earth. Be able to describe how this is evidence that the earth is a differentiated planet (figures 18.15-18.22 will help a lot). Also, be able to relate material properties at the surface to the level of “property” damage that occurs due to an earthquake of a given magnitude. Chapter 17 Understand the theories of continental drift and plate tectonics, the difference between the two, and the evidences for each. Understand paleomagnetism, how it is recorded in the rock record (both on continents and in the seafloor), and why it is important. Know the major plates and types of plate boundaries. Know how we determine plate boundaries. Know the processes that occur at convergent and divergent plate boundaries (e.g., seismicity, magmatism, metamorphism, structural features, etc). Know how magmatism occurs at divergent and convergent plate margins. In other words, understand how plate tectonics explains the dynamic evolution of the earth evident at the surface. Chapter 23 Understand the relationship between tectonism, the hydrologic cycle, differential erosion, and climate in the production of landforms. Know the relationship between elevation, erosion, and isostasy. Figure 23.4, 5 Know the primary geomorphic landscapes that occur on all continents (there are three of them Shield, stable platform, folded mountain belt). Also know these geomorphic landscapes that occur on some continents: rift systems and magmatic arcs. Know how these geomorphic provinces form and the distinctive landforms that develop for each – pay special attention to the examples from the US. The production of landforms play a key role in determining the rock types exposed at the surface. Know how the basic rock types exposed at the surface of the continent relate to geomorphic landscapes. In other words, understand the processes that influence the evolution of landforms and how these landforms relate to tectonic setting. Earth Science NR 410102 Engineering Geology Geology1 Oceanography Object of class Metamorphic Rocks Transform Plate Boundaries MAIN IDEA Transform plate boundaries are zones of shearing where plates slide horizontally past each other. In the process, lithosphere is neither created nor consumed but significant topographic features are produced. SUPPORTING IDEAS 1. There are three major types of transform boundaries: (a) ridge-ridge, (b) ridge-trench, and (c) trench-trench. 2. The shearing process involved with transform boundaries produces parallel ridges and troughs, pull-apart basins, and folds. 3. Transform faults are related to large fracture zones that may extend thousands of kilometers across the ocean floor. 4. Oceanic fracture zones may be several kilometers wide. The structure and topography of fracture zones are generally related to spreading rate. 5. Continental transform faults are similar to oceanic transforms, but they lack the fracture zone extensions. 6. Shallow earthquakes are common along transform boundaries but not along the inactive fracture zones. 7. Volcanism is rare along transforms, but locally, basaltic extrusions result from “leaky” transforms. 8. Metamorphism along transform boundaries produces rocks with a strongly sheared fabric as well as hydrated oceanic basalts. REQUIRED COMPETENCE Students will become familiar with the characteristics of transform faults and associated fracture zones and will learn how they are produced by the global tectonic system. After studying this chapter, they will be able to: 1. Recognize the global pattern of transform boundaries and identify the major types. 2. Explain the difference between transform faults and fracture zones. 3. Describe the characteristics of the Romanche and Clipperton fracture zones. 4. Explain how compression and tensional structures are produced along fracture zones. 5. Explain how the midocean ridge produces a distinctive thermal structure where it butts against a transform fault. 6. Describe the characteristics of the San Andreas, Dead Sea, and Alpine transform systems. DISCUSSION QUESTIONS What are the most significant characteristics of transform plate boundaries? 1. What type of movement occurs along a transform fault? 2. How are transforms related to the oceanic ridge? 3. What are the major topographic features produced along transform boundaries? 4. How are transform faults related to fracture zones? 5. What are the major types of transform faults? Why are they called “transform”? What are the characteristics of oceanic transform faults and associated fracture zones? 1. What are their lengths? Their widths? 2. Why might a cliff on the side of a fracture zone be on one side and then the other? 3. What is the thermal structure of a transform? 4. Why does slow shearing produce different features than those produced by fast shearing transforms? What are the characteristics of continental transform boundaries? 1. What are the typical topographic features produces along continental transforms? 2. Compare the San Andreas, Dead Sea, and Alpine transform boundaries. How are they similar? How do they differ? 3. What type of seismic activity occurs along transform boundaries? Geology FINAL Physical Geology content Introducing Geology and an Overview of Important Concepts 3 Who Needs Geology? 4 Supplying Things We Need 4 Protecting the Environment 5 Avoiding Geologic Hazards 5 Understanding Our Surroundings 8 Earth Systems 9 An Overview of Physical Geology-Important Concepts 10 Internal Processes: How the Earth''s Internal Heat Engine Works 12 Earth''s Interior 12 The Theory of Plate Tectonics 13 Surficial Processes: The Earth''s External Heat Engine 16 Geologic Time 17 SUMMARY 21 Atoms, Elements, and Minerals 25 Introduction 26 Atoms and Elements 27 Chemical Activity 30 Ions 30 Chemical Composition of the Earth''s Crust 30 Crystallinity 32 The Silicon-Oxygen Tetrahedron 33 Nonsilicate Minerals 35 Minerals 35 Crystalline Solid 37 Geologic Processes 37 Specific Chemical Composition 37 The Important Minerals 37 The Physical Properties of Minerals 40 Color 40 Streak 40 Luster 40 Hardness 40 External Crystal Form 41 Cleavage 43 Fracture 44 Specific Gravity 45 Special Properties 46 Other Properties 46 Chemical Tests 47 SUMMARY 47 Igneous Rocks, Intrusive Activity, and the Origin of Igneous Rocks 51 The Rock Cycle 52 A Plate-Tectonic Example 53 Igneous Rocks 53 Igneous Rock Textures 55 Identification of Igneous Rocks 57 Varieties of Granite 58 Chemistry of Igneous Rocks 58 Intrusive Bodies 60 Shallow Intrusive Structures 60 Intrusives That Crystallize at Depth 61 Abundance and Distribution of Plutonic Rocks 63 How Magma Forms 64 Heat for Melting Rock 64 Factors That Control Melting Temperatures 64 How Magmas of Different Compositions Evolve 66 Sequence of Crystallization and Melting 66 Differentiation 67 Partial Melting 68 Assimilation 68 Mixing of Magmas 69 Explaining Igneous Activity by Plate Tectonics 69 Igneous Processes at Divergent Boundaries 69 Intraplate Igneous Activity 69 Igneous Processes at Convergent Boundaries 70 SUMMARY 73 Volcanism and Extrusive Rocks 77 Introduction 78 Living with Volcanoes 81 Supernatural Beliefs 81 The Growth of an Island 81 Geothermal Energy 81 Effect on Climate 81 Volcanic Catastrophes 81 Eruptive Violence and Physical Characteristics of Lava 84 Extrusive Rocks and Gases 85 Scientific Investigation of Volcanism 85 Gases 85 Extrusive Rocks 86 Composition 86 Extrusive Textures 87 Types of Volcanoes 89 Shield Volcanoes 90 Cinder Cones 92 Composite Volcanoes 94 Volcanic Domes 96 Lava Floods 99 Submarine Eruptions 100 Pillow Basalts 100 SUMMARY 102 Weathering and Soil 107 Weathering, Erosion, and Transportation 108 Weathering and Earth Systems 108 Solar System 108 Atmosphere 109 Hydrosphere 109 Biosphere 109 How Weathering Alters Rock 109 Effects of Weathering 109 Mechanical Weathering 111 Frost Action 111 Pressure Release 111 Other Processes 111 Chemical Weathering 113 Role of Oxygen 114 Role of Acids 114 Solution Weathering 114 Chemical Weathering of Feldspar 116 Chemical Weathering of Other Minerals 116 Weathering Products 118 Weathering and Climate 118 Soil 118 Soil Horizons 119 Soil Classification 119 Residual and Transported Soils 120 Soils, Parent Material, Time, and Slope 120 Organic Activity 122 Soils and Climate 122 Buried Soils 124 SUMMARY 124 Sediment and Sedimentary Rocks 127 Sediment 129 Transportation 129 Deposition 130 Preservation 131 Lithification 132 Types of Sedimentary Rocks 133 Clastic Rocks 133 Breccia and Conglomerate 133 Sandstone 135 The Fine-Grained Rocks 136 Chemical Sedimentary Rocks 137 Carbonate Rocks 137 Chert 141 Evaporites 141 Organic Sedimentary Rocks 142 Coal 142 The Origin of Oil and Gas 142 Sedimentary Structures 142 Formations 147 Interpretation of Sedimentary Rocks 148 Source Area 148 Environment of Deposition 150 Plate Tectonics and Sedimentary Rocks 152 SUMMARY 153 Metamorphism, Metamorphic Rocks, and Hydrothermal Rocks 157 Introduction 158 Factors Controlling the Characteristics of Metamorphic Rocks 159 Composition of the Parent Rock 160 Temperature 160 Pressure 160 Fluids 162 Time 162 Classification of Metamorphic Rocks 163 Types of Metamorphism 163 Contact Metamorphism 163 Regional Metamorphism 165 Plate Tectonics and Metamorphism 169 Hydrothermal Processes 172 Hydrothermal Activity at Divergent Plate Boundaries 172 Water at Convergent Boundaries 173 Metasomatism 173 Hydrothermal Rocks and Minerals 174 SUMMARY 176 Time and Geology 179 The Key to the Past 180 Relative Time 181 Principles Used to Determine Relative Age 181 Unconformities 186 Correlation 187 The Standard Geologic Time Scale 191 Numerical Age 193 Isotopic Dating 193 Uses of Isotopic Dating 196 Combining Relative and Numerical Ages 198 Age of the Earth 199 Comprehending Geologic Time 201 SUMMARY 201 Mass Wasting 205 Classification of Mass Wasting 206 Rate of Movement 206 Type of Material 206 Type of Movement 206 Controlling Factors in Mass Wasting 208 Gravity 210 Water 210 Triggering Mechanisms 211 Common Types of Mass Wasting 212 Creep 212 Debris Flow 213 Rockfalls and Rockslides 217 Underwater Slides 220 Preventing Landslides 221 Preventing Mass Wasting of Debris 221 Preventing Rockfalls and Rockslides on Highways 222 SUMMARY 224 Streams and Floods 227 Earth Systems-The Hydrologic Cycle 229 Channel Flow and Sheet Flow 229 Drainage Basins 230 Drainage Patterns 231 Factors Affecting Stream Erosion and Deposition 231 Velocity 232 Gradient 233 Channel Shape and Roughness 233 Discharge 234 Stream Erosion 235 Stream Transportation of Sediment 236 Stream Deposition 237 Bars 237 Braided Streams 240 Meandering Streams and Point Bars 241 Flood Plains 243 Deltas 243 Alluvial Fans 246 Kaibab Limestone Toroweap Formation Coconino Sandstone Hermit Shale Supai Formation Redwall Limestone Hermit Shale Supai Formation Redwall Limestone Flooding 246 Urban Flooding 247 Flash Floods 247 Controlling Floods 251 The Great Flood of 1993 251 Stream Valley Development 253 Downcutting and Base Level 253 The Concept of a Graded Stream 253 Lateral Erosion 255 Headward Erosion 255 Stream Terraces 256 Incised Meanders 257 Superposed Streams 257 SUMMARY 259 Ground Water 263 Introduction 264 Porosity and Permeability 264 The Water Table 265 The Movement of Ground Water 267 Aquifers 268 Wells 269 Springs and Streams 270 Contamination of Ground Water 272 Balancing Withdrawal and Recharge 277 Effects of Ground-Water Action 277 Caves, Sinkholes, and Karst Topography 277 Other Effects 280 Hot Water Underground 281 Geothermal Energy 282 SUMMARY 283 Glaciers and Glaciation 287 The Theory of Glacial Ages 288 Glaciers-What They Are, How They Form and Move 289 Distribution of Glaciers 289 Types of Glaciers 289 Formation and Growth of Glaciers 291 Movement of Valley Glaciers 292 Movement of Ice Sheets 296 Glacial Erosion 298 Erosional Landscapes Associated with Alpine Glaciation 298 Erosional Landscapes Associated with Continental Glaciation 301 Glacial Deposition 302 Moraines 303 Outwash 305 Glacial Lakes and Varves 306 Effects of Past Glaciation 308 The Glacial Ages 308 Direct Effects of Past Glaciation in North America 309 Indirect Effects of Past Glaciation 310 Evidence for Older Glaciation 311 SUMMARY 313 Deserts and Wind Action 317 Distribution of Deserts 318 Some Characteristics of Deserts 319 Desert Features in the Southwestern United States 322 Wind Action 326 Wind Erosion and Transportation 326 Wind Deposition 328 SUMMARY 330 Waves, Beaches, and Coasts 339 Introduction 340 Water Waves 340 Surf 341 Near-shore Circulation 342 Wave Refraction 342 Longshore Currents 342 Rip Currents 342 Beaches 344 Longshore Drift of Sediment 345 Human Interference with Sand Drift 346 Sources of Sand on Beaches 348 Coasts and Coastal Features 348 Erosional Coasts 349 Depositional Coasts 350 Drowned Coasts 351 Uplifted Coasts 352 The Biosphere and Coasts 353 SUMMARY 356 Geologic Structures 359 Introduction 360 Tectonic Forces at Work 360 Stress and Strain in the Earth''s Crust 360 Behavior of Rocks to Stress and Strain 361 Present Deformation of the Crust 362 Structures as a Record of the Geologic Past 362 Geologic Maps and Field Methods 362 Folds 365 Geometry of Folds 365 Interpreting Folds 368 Fractures in Rock 369 Joints 369 Faults 370 SUMMARY 379 Earthquakes 383 Introduction 384 Causes of Earthquakes 386 Seismic Waves 387 Body Waves 388 Surface Waves 389 Locating and Measuring Earthquakes 389 Determining the Location of an Earthquake 389 Measuring the Size of an Earthquake 392 Location and Size of Earthquakes in the United States 395 Effects of Earthquakes 395 Tsunami 399 World Distribution of Earthquakes 403 First-Motion Studies of Earthquakes 403 Earthquakes and Plate Tectonics 405 Earthquakes at Plate Boundaries 405 Subduction Angle 407 Earthquake Prediction and Seismic Risk 407 SUMMARY 412 Earth''s Interior and Geophysical Properties 417 Introduction 418 Evidence from Seismic Waves 418 Earth''s Internal Structure 421 The Crust 421 The Mantle 422 The Core 424 Isostasy 428 Gravity Measurements 429 Earth''s Magnetic Field 432 Magnetic Reversals 433 Magnetic Anomalies 434 Heat Within the Earth 437 Geothermal Gradient 437 Heat Flow 438 SUMMARY 439 The Sea Floor 443 Origin of the Ocean 444 Methods of Studying the Ocean Floor 444 Features of the Sea Floor 446 Continental Shelves and Continental Slopes 446 Submarine Canyons 448 Turbidity Currents 449 Passive Continental Margins 450 The Continental Rise 451 Abyssal Plains 451 Active Continental Margins 452 Oceanic Trenches 452 The Mid-Oceanic Ridge 453 Geologic Activity on the Ridge 453 Biologic Activity on the Ridge 455 Fracture Zones 455 Seamounts, Guyots, and Aseismic Ridges 456 Reefs 457 Sediments of the Sea Floor 459 Oceanic Crust and Ophiolites 459 The Age of the Sea Floor 462 The Sea Floor and Plate Tectonics 462 SUMMARY 462 Plate Tectonics 467 The Early Case for Continental Drift 469 Skepticism About Continental Drift 472 Paleomagnetism and the Revival of Continental Drift 472 Recent Evidence for Continental Drift 473 History of Continental Positions 474 Seafloor Spreading 474 Hess''s Driving Force 474 Explanations 475 Plates and Plate Motion 476 How Do We Know That Plates Move? 477 Marine Magnetic Anomalies 477 Another Test: Fracture Zones and Transform Faults 480 Measuring Plate Motion Directly 480 Divergent Plate Boundaries 481 Transform Boundaries 484 Convergent Plate Boundaries 485 Ocean-Ocean Convergence 486 Ocean-Continent Convergence 487 Continent-Continent Convergence 489 Backarc Spreading 490 The Motion of Plate Boundaries 490 Plate Size 491 The Attractiveness of Plate Tectonics 491 What Causes Plate Motions? 492 Mantle Plumes and Hot Spots 494 The Relationship Between Plate Tectonics and Ore Deposits 497 A Final Note 498 SUMMARY 499 Mountain Belts and the Continental Crust 503 Characteristics of Major Mountain Belts 506 Size and Alignment 506 Ages of Mountain Belts and Continents 506 Thickness and Characteristics of Rock Layers 508 Patterns of Folding and Faulting 508 Metamorphism and Plutonism 510 Normal Faulting 510 Thickness and Density of Rocks 510 Features of Active Mountain Ranges 511 The Evolution of a Mountain Belt 511 The Accumulation Stage 511 The Orogenic Stage 512 The Uplift and Block-Faulting Stage 515 The Growth of Continents 520 Displaced Terranes 520 SUMMARY 522 Geologic Resources 525 Types of Resources 526 Resources and Reserves 527 Energy Use 527 Oil and Natural Gas 528 The Occurrence of Oil and Gas 528 Recovering the Oil 529 How Much Petroleum Do We Have Left? 530 Heavy Crude and Oil Sands 530 Oil Shale 532 Coal 532 Varieties of Coal 532 Occurrence of Coal 533 Environmental Effects 535 Reserves and Resources 535 Uranium 535 Alternative Sources of Energy 536 Metals and Ores 536 Origin of Metallic Ore Deposits 536 Ores Associated with Igneous Rocks 537 Ores Formed by Surface Processes 538 Mining 539 Environmental Effects 539 Some Important Minerals 540 Iron 540 Copper 541 Aluminum 541 Lead 541 Zinc 542 Silver 542 Gold 542 Other Metals 543 Nonmetallic Resources 543 Construction Materials 543 Fertilizers and Evaporites 544 Other Nonmetallics 544 Some Future Trends 544 The Human Perspective 544 SUMMARY 545 The Earth''s Companions 549 The Earth in Space 550 The Sun 550 The Solar System 550 The Milky Way and the Universe 554 Origin of the Planets 554 The Solar Nebula 554 Formation of the Planets 556 Formation of Moons 557 Final Stages of Planet Formation 557 Formation of Atmospheres 557 Other Planetary Systems 557 Portraits of the Planets 558 Our Moon 558 Description of the Moon 559 Structure of the Moon 562 Origin and History of the Moon 562 Mercury 564 Venus 565 Mars 566 Why Are the Terrestrial Planets So Different? 570 Jupiter 571 Saturn 573 Uranus 574 Neptune 574 Pluto 575 Minor Objects of the Solar System 575 Meteors and Meteorites 575 Asteroids 576 Comets 576 Giant Impacts 578 Giant Meteor Impacts 578 SUMMARY 579