Introduction 1
About This Book 1
Foolish Assumptions 2
Icons Used in This Book 2
Beyond the Book 3
Where to Go from Here 3
Part 1: Studying The Earth 5
Chapter 1: Rocks for Jocks (and Everybody Else) 7
Finding Your Inner Scientist 8
Making observations every day 8
Jumping to conclusions 8
Focusing on Rock Formation and Transformation 8
Understanding how rocks form 9
Tumbling through the rock cycle 9
Mapping Continental Movements 10
Unifying geology with plate tectonics theory 10
Debating a mechanism for plate movements 11
Moving Rocks around on Earth’s Surface 11
Interpreting a Long History of Life on Earth 12
Using relative versus absolute dating 12
Witnessing evolution in the fossil record 13
Chapter 2: Observing Earth through a Scientific Lens 15
Realizing That Science Is Not Just for Scientists 15
Using a Methodical Approach: The Scientific Method 16
Sensing something new 17
I have a hypothesis! 18
Testing your hypothesis: Experiments 18
Crunching the numbers 19
Interpreting results 21
Sharing the findings 21
Building New Knowledge: A Scientific Theory 21
It’s never “just a theory” 22
Scientific theory versus scientific law 22
The road to paradigms 23
Speaking in Tongues: Why Geologists Seem to Speak a Separate Language 23
Lamination vs foliation: Similar outcomes from different processes 24
Gabbro vs basalt: Different outcomes from similar processes 24
Chapter 3: From Here to Eternity: The Past, Present, and Future of Geologic Thought 27
Catastrophe Strikes Again and Again 28
Early Thoughts on the Origin of Rocks 28
Developing Modern Geologic Understanding 29
Reading the rock layers: Steno’s stratigraphy 29
These things take time! Hutton’s hypothesis 30
What has been will be: Lyell’s principles 31
Uniformi-what? Understanding the Earth through Uniformitarianism 32
Pulling It All Together: The Theory of Plate Tectonics 32
Forging Ahead into New Frontiers 33
Asking how, where, and why: Mountain building and plate boundaries 33
Mysteries of the past: Snowball earth, first life, and mass extinctions 34
Predicting the future: Earthquakes and climate change 35
Out of this world: Planetary geology and the search for life 37
Chapter 4: Home Sweet Home: Planet Earth 39
Earth’s Spheres 39
Examining Earth’s Geosphere 41
Defining Earth’s layers 41
Examining each layer 43
Part 2: Elements, Minerals, And Rocks 49
Chapter 5: It’s Elemental, My Dear: A Very Basic Chemistry of Elements and Compounds 51
The Smallest Matter: Atoms and Atomic Structure 52
Getting to know the periodic table 53
Interpreting isotopes 56
Charging particles: Ions 56
Chemically Bonding 57
Donating electrons (ionic bonds) 57
Sharing electrons (covalent bonds) 57
Migrating electrons (metallic bonds) 58
Formulating Compounds 60
Chapter 6: Minerals: The Building Blocks of Rocks 61
Meeting Mineral Requirements 62
Making Crystals 62
Identifying Minerals Using Physical Characteristics 63
Observing transparency, color, luster, and streak 63
Measuring mineral strength 64
If it tastes like salt, it must be halite: Noting unique mineral properties 68
Measuring properties in the lab 69
Realizing Most Rocks Are Built from Silicate Minerals 70
Finding silicates in many shapes 71
Grouping silicate minerals 74
Remembering the Nonsilicate Minerals 74
Carbonates 74
Sulfides and sulfates 75
Oxides 75
Native elements 76
Evaporites 76
Gemstones 77
Chapter 7: Recognizing Rocks: Igneous, Sedimentary, and Metamorphic Types 79
Mama Magma: Birthing Igneous Rocks 80
Remembering how magma is made 80
Classifying melt composition 81
Reacting in sequence: Bowen’s reaction series 81
Evolving magmas 83
Crystallizing one way or another: Igneous rocks 84
Classifying igneous rocks 85
Studying volcanic structures 89
Looking below the surface 92
Merging Many Single Grains of Sand: Sedimentary Rocks 94
Weathering rocks into sediments 95
Changing from sediment into rock 98
Sizing up the grains: Classifying sedimentary rocks 99
Searching for sedimentary basins 102
Telling stories of the past: Sedimentary structures 103
Stuck between a Rock and a Hard Place: Metamorphic Rocks 106
Turning up the heat and pressure: Metamorphism 106
Grading metamorphism with index minerals 107
Between the mineral sheets: Foliation, or maybe not 108
Categorizing metamorphic rocks 110
Tumbling through the Rock Cycle: How Rocks Change from One Type to Another 112
Part 3: One Theory To Explain It All: Plate Tectonics 115
Chapter 8: Adding Up the Evidence for Plate Tectonics 117
Drifting Apart: Wegener’s Idea of Continental Drift 118
Continental puzzle solving 118
Fossil matching 119
Stratigraphic stories 120
Icy cold climates of long ago 122
Meeting at the equator 123
Searching for a mechanism 123
Coming Together: How Technology Sheds Light on Plate Tectonics 124
Mapping the seafloor 124
Flip-flopping magnetic poles: Paleomagnetism and seafloor spreading 125
Measuring plate movements 127
Unifying the theory 127
Chapter 9: When Crustal Plates Meet, It’s All Relative 129
Density Is Key 130
Two of a Kind: Continental and Oceanic Crust 131
Dark and dense: Oceanic crust 131
Thick and fluffy: Continental crust 131
Understanding Why Density Matters: Isostasy 132
Defining Plate Boundaries by Their Relative Motion 133
Driving apart: Divergent plate boundaries 134
Crashing together: Convergent plate boundaries 136
Slip-sliding along: Transform plate boundaries 139
Shaping Topography with Plate Movements 141
Deforming the crust at plate boundaries 141
Compressing rocks into folds 142
Faulting in response to stress 144
Building mountains 146
Chapter 10: Who’s Driving This Thing? Mantle Convection and Plate Movement 149
Running in Circles: Models of Mantle Convection 150
Mantle plumes: Just like the lava in your lamp 152
The slab-pull and ridge-push models 152
Using Convection to Explain Magma, Volcanoes, and Underwater Mountains 153
Plate friction: Melting rock beneath the earth’s crust 154
Creating volcanic arcs and hotspots 154
Birthing new seafloor at mid-ocean ridges 158
Shake, Rattle, and Roll: How Plate Movements Cause Earthquakes 158
Responding elastically 159
Sending waves through the earth 160
Measuring magnitude 160
Part 4: Superficially Speaking: About Surface Processes 163
Chapter 11: Gravity Takes Its Toll: Mass Wasting 165
Holding Steady or Falling Down: Friction versus Gravity 166
Focusing on the Materials Involved 167
Loose materials: Resting at the angle of repose 167
Bedrock: Losing its stability 168
Triggering Mass Movements 168
Adding water to the mix 168
Changing the slope angle 169
Shaking things up: Earthquakes 170
Removing vegetation 170
Moving Massive Amounts of Earth, Quickly 171
Falls 171
Slides and slumps 171
Flows 172
A More Subtle Approach: Creep and Soil Flow (Solifluction) 173
Chapter 12: Water: Above and Below Ground 175
Hydrologic Cycling 176
Driving the cycle with evaporation 176
Traveling across a continent 177
Streams: Moving Sediments toward the Ocean 178
Draining the basin 178
Two types of flow 179
Measuring stream characteristics 180
Carrying a heavy load 180
Measuring what is transported 181
Eroding a Stream Channel to Base Level 182
Seeking Equilibrium after Changes in Base Level 183
Leaving Their Mark: How Streams Create Landforms 184
Draining the basin 184
Meandering along 185
Depositing sediments along the way 187
Reaching the sea 187
Flowing beneath Your Feet: Groundwater 188
Infiltrating tiny spaces underground 188
Measuring porosity and permeability 189
Setting the water table 189
Springing from rocks 190
That sinking feeling: Karst, caves, and sinkholes 192
Chapter 13: Flowing Slowly toward the Sea: Glaciers 195
Identifying Three Types of Glaciers 196
Understanding Ice as a Geologic Force 196
Transforming snow into ice 197
Balancing the glacial budget 197
Flowing solidly down the mountain 198
Eroding at a Snail’s Pace: Landforms Created by Glacial Erosion 199
Plucking and abrading along the way 200
Creating their own valleys 200
Speaking French: Cirques, aretes, et roche moutonnees 201
Leaving It All Behind: Glacial Deposits 203
Depositing the till 203
Plains, trains, eskers, and kames 204
Behaving erratically: Large boulders in odd places 206
Where Have All the Glaciers Gone? 206
Filling the erosional gaps 206
Cycling through ice ages 207
Rebounding isostatically 209
Chapter 14: Blowing in the Wind: Moving Sediments without Water 211
Lacking Water: Arid Regions of the Earth 212
Transporting Particles by Air 212
Skipping right along: Bed load and saltation 213
Suspending particles in air 214
Deflating and Abrading: Features of Wind Erosion 214
Removing sediments 215
Scratching the surface 215
Just Add Wind: Dunes and Other Depositional Wind Features 216
Migrating piles of sand: Dunes 217
Shaping sand 218
Laying down layers of loess 219
Paving the Desert: Deposition or Erosion? 221
Chapter 15: Catch a Wave: The Evolution of Shorelines 223
Breaking Free: Waves and Wave Motion 223
Dissecting wave anatomy 223
Starting to roll 224
Going with the flow: Currents and tides 226
Shaping Shorelines 228
Carving cliffs and other features 228
Budgeting to build sandbars 228
Categorizing Coastlines 230
Part 5: Long, Long Ago In This Galaxy Right Here 233
Chapter 16: Getting a Grip on Geologic Time 235
The Layer Cake of Time: Stratigraphy and Relative Dating 236
Speaking relatively 236
Sorting out the strata 236
Putting rock layers in the right order 237
Losing time in the layers 238
Show Me the Numbers: Methods of Absolute Dating 240
Measuring radioactive decay 241
Common radioactive isotopes for geological dating 244
Other exacting methods of geological dating 245
Relatively Absolute: Combining Methods for the Best Results 248
Eons, Eras, and Epochs (Oh My!): Structuring the Geologic Timescale 249
Chapter 17: A Record of Life in the Rocks 253
Explaining Change, Not Origins: The Theory of Evolution 254
The Evolution of a Theory 254
Acquiring traits doesn’t do it 254
Naturally, selecting for survival 255
Mendel’s peas please 255
Genetic nuts and bolts 256
Spontaneously mutating genes 256
Speciating right and left 257
Putting Evolution to the Test 258
Against All Odds: The Fossilization of Lifeforms 259
Bones, teeth, and shell: Body fossils 259
Just passing through: Trace fossils 260
Correcting for Bias in the Fossil Record 261
Hypothesizing Relationships: Cladistics 262
Chapter 18: Time before Time Began: The Precambrian 265
In the Beginning Earth’s Creation from a Nebulous Cloud 266
Addressing Archean Rocks 267
Creating continents 267
Revving up the rock cycle 267
Feeling hot, hot, hot: Evidence for extreme temperatures 269
Originating with Orogens: Supercontinents of the
Proterozoic Eon 270
Single Cells, Algal Mats, and the Early Atmosphere 271
Hunting early prokaryotes and eukaryotes 271
You know it as pond scum: Cyanobacteria 272
Waiting to inhale: The formation of Earth’s atmosphere 275
Questioning the Earliest Complex Life: The Ediacaran Fauna 278
Chapter 19: Teeming with Life: The Paleozoic Era 281
Exploding with Life: The Cambrian Period 282
Toughen up! Developing shells 282
Ruling arthropods of the seafloor: Trilobites 283
Building Reefs All Over the Place 284
Swimming freely: Ammonoids and nautiloids 285
Exploring freshwater: Eurypterids 287
Spinal Tapping: Animals with Backbones 287
Fish evolve body armor, teeth, and legs? 287
Venturing onto land: Early amphibians 290
Adapting to life on land: The reptiles 290
Planting Roots: Early Plant Evolution 291
Tracking the Geologic Events of the Paleozoic 293
Constructing continents 293
Reading the rocks: Transgressions and regressions 294
Fossilizing carbon fuels 297
Pangaea, the most super of supercontinents 297
Chapter 20: Mesozoic World: When Dinosaurs Dominated 299
Driving Pangaea Apart at the Seams 300
One continent becomes many 300
Influencing global climate 301
Creating the mountains of North America 302
Repopulating the Seas after Extinction 303
The Symbiosis of Flowers 304
Recognizing All the Mesozoic Reptiles 306
Flocking together 308
Climbing the Dinosaur Family Tree 308
Branching out: Ornithischia and Saurischia 308
Horned faces and armor: Ornithischian dinosaurs 309
Long necks and meat eaters: Saurischian dinosaurs 312
Flocking Together: The Evolutionary Road to Birds 313
Laying the Groundwork for Later Dominance: Early
Mammal Evolution 314
Chapter 21: The Cenozoic Era: Mammals Take Over 315
Putting Continents in Their Proper (Okay, Current) Places 316
Creating modern geography 316
Consuming the Farallon Plate 317
Carving the Grand Canyon with uplift 319
Icing over northern continents 320
Entering the Age of Mammals 320
Regulating body temperature 322
Filling every niche 323
Living Large: Massive Mammals Then and Now 323
Nosing around elephant evolution 324
Returning to the sea: Whales 325
Larger than life: Giant mammals of the ice ages 326
Right Here, Right Now: The Reign of Homo Sapiens 327
Arguing for the Anthropocene 329
Altering the climate 329
Shaping the landscape 330
Leaving evidence in the rock record 332
Chapter 22: And Then There Were None: Major Extinction Events in Earth’s History 333
Explaining Extinctions 334
Heads up! Astronomical impacts 334
Lava, lava everywhere: Volcanic eruptions and flood basalts 335
Shifting sea levels 337
Changing climate 337
End Times, at Least Five Times 337
Cooling tropical waters 338
Reducing carbon dioxide levels 338
The Great Dying 339
Paving the way for dinosaurs 340
Demolishing dinosaurs: The K/T boundary 340
Modern Extinctions and Biodiversity 342
Hunting the megafauna 342
Reducing biodiversity 343
Part 6: The Part of Tens 345
Chapter 23: Ten Ways You Use Geologic Resources Every Day 347
Burning Fossil Fuels 347
Playing with Plastics 348
Gathering Gemstones 348
Drinking Water 349
Creating Concrete 349
Paving Roads 350
Accessing Geothermal Heat 350
Fertilizing with Phosphate 350
Constructing Computers 351
Building with Beautiful Stone 351
Chapter 24: Ten Geologic Hazards 353
Changing Course: River Flooding 353
Caving In: Sinkholes 354
Sliding Down: Landslides 354
Shaking Things Up: Earthquakes 355
Washing Away Coastal Towns: Tsunamis 355
Destroying Farmland and Coastal Bluffs: Erosion 356
Fiery Explosions of Molten Rock: Volcanic Eruptions 356
Melting Ice with Fire: Jokulhlaups 357
Flowing Rivers of Mud: Lahars 357
Watching the Poles: Geomagnetism 358
Index 359
