Geology Cheatsheet
Plate Tectonics
Plate Boundaries
- Divergent boundary: where two plates move away from each other
- Convergent boundary: where two plates move towards each other
- Subduction zone: where an oceanic plate is forced beneath a continental plate
- Collision zone: where two continental plates collide
- Transform boundary: where two plates slide past each other
Volcanoes
- Shield volcano: broad, gently sloping, with effusive eruptions
- Cinder cone volcano: steep, conical, with explosive eruptions
- Stratovolcano (composite volcano): large, steep-sided, with alternating layers of lava and ash
Earthquakes
- Focus: the point beneath the Earth’s surface where the earthquake starts
- Epicenter: the point on the Earth’s surface directly above the focus
- Seismic waves: the waves of energy that travel through the Earth
Rocks and Minerals
Rock Types
- Igneous rock: formed from cooling and solidification of magma or lava
- Sedimentary rock: formed from the accumulation and lithification of sediment
- Metamorphic rock: formed from the alteration of pre-existing rock under high temperature and/or pressure
Mineral Properties
- Color: the color of the mineral
- Luster: the way the mineral reflects light
- Hardness: the resistance of the mineral to scratching
- Cleavage: the way the mineral breaks along planes of weakness
- Fracture: the way the mineral breaks along curved or irregular surfaces
Geologic Time Scale
- Eon: the largest division of time, based on the abundance of fossils
- Phanerozoic eon: the most recent eon, characterized by the proliferation of complex life forms
- Era: a subdivision of an eon, based on significant events in Earth’s history
- Mesozoic era: the era of the dinosaurs
- Period: a subdivision of an era, based on distinctive rock layers
- Jurassic period: the period of the dinosaurs
- Epoch: a subdivision of a period, based on smaller-scale changes in Earth’s history
- Holocene epoch: the current epoch, characterized by the rise of human civilization
Resources