Geology

How Earth formed and sorted into layers, how earthquake waves reveal the inside, and how heat, buoyancy and magnetism shape the crust.

1. How Earth Formed and Layered
2. Seeing Inside Earth with Seismic Waves
3. Heat Flow and the Geothermal Gradient
4. Isostasy: How Crust Floats
5. Earth's Magnetic Field in Rocks

How atoms build crystals, the silicate families that make up most rock, and the other mineral groups.

1. Atoms, Ions and Crystals
2. The Silica Tetrahedron
3. Silicate Families
4. Carbonates, Oxides, Sulfides and Other Groups

How rock melts, how magma crystallizes and is named, where it cools underground, and why some eruptions explode.

1. How Rocks Melt
2. Bowen's Reaction Series
3. Mafic to Felsic
4. Naming Igneous Rocks
5. Plutons, Dikes and Sills
6. Gentle and Explosive Eruptions
7. Volcanic Hazards and Monitoring

How weathering makes sediment, how flowing water sorts it, and how layers record the places they formed.

1. Chemical Weathering Reactions
2. Grain Size and the Wentworth Scale
3. How Flowing Water Moves Sediment
4. Sorting, Rounding and Maturity
5. Naming Sedimentary Rocks
6. Reading Sedimentary Structures
7. Depositional Environments

How heat, pressure and fluids change rock, how to read metamorphic grade, and where metamorphism happens.

1. Heat and Pressure with Depth
2. Foliation and Metamorphic Grade
3. Naming Metamorphic Rocks
4. Where Metamorphism Happens

How rocks bend and break under stress, and how geologists describe tilted and folded layers.

1. Stress and Strain
2. Anticlines, Synclines and Domes
3. Normal, Reverse and Strike-Slip Faults
4. Strike and Dip

Ordering events with Steno's principles and unconformities, dating rocks with radioactive clocks, and the great events of Earth's history.

1. Steno's Principles and Faunal Succession
2. Unconformities
3. Correlating Rock Layers
4. Reconstructing a Region's History
5. Radiometric Dating
6. Choosing a Radioactive Clock
7. Combining Relative and Absolute Ages
8. Major Events in Earth's History

Measuring plate motion, what drives it, the anatomy of each kind of boundary, and how oceans open and close.

1. Magnetic Stripes and Spreading Rates
2. Measuring Plate Motion with GPS
3. What Drives the Plates
4. Subduction Zones
5. Continental Collisions and Rifts
6. Transform Faults
7. The Wilson Cycle

Why faults slip, locating an earthquake, measuring its size and shaking, forecasting the odds, and tsunamis.

1. Elastic Rebound
2. Distance from the S–P Time
3. Finding the Epicenter
4. Moment Magnitude and Energy
5. Intensity and Ground Shaking
6. Earthquake Forecasts as Probabilities
7. Tsunamis

Slopes, rivers, floods, groundwater and glaciers: the processes that shape the land and the numbers that describe them.

1. Landslides and Slope Stability
2. Stream Gradient and Discharge
3. Meanders, Floodplains and Base Level
4. What a 100-Year Flood Means
5. Groundwater Flow and Darcy's Law
6. Glaciers: Mass Balance and Flow

How ore deposits and fossil fuels form, and how reserves are counted.

1. How Ore Deposits Form
2. How Oil, Gas and Coal Form
3. Resources, Reserves and How Long They Last