The Science of Geology

Vocabulary flashcards covering core geology concepts from the lecture notes, including Earth’s interior, plate tectonics, and paleomagnetism.

Geology

The science that pursues an understanding of planet Earth.

Physical geology

The branch examining materials composing Earth and the processes operating beneath and on its surface.

Historical geology

The branch seeking to understand the origin of Earth and its development through time.

Natural hazards

Hazards from natural processes (volcanoes, floods, tsunamis, earthquakes, landslides) that become dangerous where people live.

Resources

Geology’s focus on water, soil, minerals, and energy resources.

Uniformitarianism

The principle that Earth’s present-day processes operate over geologic time, shaping the past as they do today.

Deep Time

The concept of an extremely long Earth history, allowing slow processes to produce major changes.

Catastrophism

The view that explosive, short-lived events have shaped Earth’s features.

James Ussher

17th‑century scholar who estimated Earth’s age as 4004 BC using biblical genealogies.

James Hutton

Geologist who proposed uniformitarianism and the idea of Deep Time; Earth changes slowly over time.

Georges Cuvier

Pioneer of catastrophism who argued for extinction and that the present is the key to the past.

Alfred Wegener

German meteorologist who proposed continental drift (1915) and the existence of Pangaea.

Pangaea

The supercontinent that existed before its breakup, underpinning the idea of continental drift.

Continental drift

The hypothesis that continents move across Earth’s surface over geologic time.

Plate tectonics

The theory that Earth’s lithosphere is broken into moving plates driven by mantle convection.

Lithosphere

The outer rigid shell of Earth (crust + upper mantle), about 100–200 km thick.

Asthenosphere

The semi‑plastic layer beneath the lithosphere that allows plate motion.

Mantle

The thick layer between crust and core; divided into upper and lower mantle.

Crust

Earth’s outermost layer; oceanic crust is thin and dense, continental crust is thicker and lighter.

Oceanic crust

Thin, dense crust (~7 km) composed mainly of basalt and gabbro.

Continental crust

Thicker, less dense crust dominated by felsic rocks.

Core

Earth’s center, consisting of a liquid outer core and a solid inner core.

Moho

The boundary between the crust and mantle, marked by a jump in P‑wave velocity.

Seismic waves

Waves produced by earthquakes used to study Earth’s interior; include P and S waves.

P waves

Primary, compressional seismic waves; travel through solids and liquids and are the fastest."

S waves

Secondary, shear seismic waves; travel only through solids and are slower than P waves.

Shadow zones

Areas where certain seismic waves are absent or weak due to the core’s properties.

Seafloor spreading

Formation of new ocean floor at mid‑ocean ridges and recycling of old crust at margins.

Paleomagnetism

Study of ancient magnetic fields recorded in rocks to infer past plate motions.

Magnetic reversals

Periodic reversals of Earth’s magnetic field where north and south poles switch.

Magnetic stripes

Symmetrical bands of normal and reversed magnetization on the ocean floor recording reversals.

Transform boundaries

Plate margins where plates slide past one another; transform faults connect other boundary types.