Alecia M. Spooner has been teaching at the college level for more than 15 years. She currently teaches at Seattle Central College, where she is Professor of Earth and Environmental Sciences. Alecia teaches earth science courses that are accessible and engaging, while stressing scientific literacy and critical thinking.

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, arêtes, et roche moutonnées 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