Foundations

Rock materials can change through multiple geological pathways.

Moving lithospheric plates organize many large-scale geological processes.

Water moves among reservoirs above, on and below Earth's surface.

Carbon moves through biological, oceanic, atmospheric and geological reservoirs.

Mineral identification combines structural and physical evidence.

Isotopic measurements estimate an age only with a suitable geological model.

Wave travel, refraction and transmission constrain an interior model.

Fluid motion in the outer core maintains much of Earth's magnetic field.

Geological history is organized into nested eons, eras, periods, epochs and ages.

Accretion, impacts, gravitational redistribution and radioactive decay contributed to early-Earth heating.

Oxygenic photosynthesis supplied oxygen while chemical reactions with reduced material consumed it.

An isotope delta compares a specified sample isotope ratio with the same ratio in a stated reference.

Gravity supplies both downslope shear and normal loading on a slope.

Coastal landforms reflect sediment supply, wave/current transport, erosion and deposition.

An ascending air parcel expands as pressure falls and can cool toward saturation.

Stress describes force per area on a specified plane; strain describes deformation.

Fold geometry includes limbs, hinge/axis and axial surface; antiform/synform describe shape while anticline/syncline also depend on stratigraphic order.

Strike is the bearing of a horizontal line in a plane; dip is the maximum inclination from horizontal, perpendicular to strike, with direction specified.

Superposition constrains age order in an undisturbed depositional sequence; inclusions predate their host, and cross-cutting features postdate what they cut.

Fossil assemblages can constrain relative age and depositional environment through observed succession and known ecological context.

Grain size, sorting, sedimentary structures, composition and fossils together constrain depositional processes and environments.

Isostasy describes buoyancy-related balance of lithospheric columns over a deformable mantle in an appropriate model.

For a locally planar bed with true dip δ, choose horizontal x toward its down-dip direction and elevation z upward.

Within a conformable depositional succession, vertically successive facies can represent environments that were laterally adjacent as the depositional system migrated.

A depositional sequence is a relatively conformable succession bounded by unconformities and their correlative conformities under the stated sequence model.

Accommodation is space available for sediment accumulation.

On a spherical rigid-plate model, displacement relative to a specified reference plate is represented by a finite rotation about an Euler pole.

Conjugate continental geology and fossils, ocean-floor magnetic reversal sequences, spreading geometry and paleomagnetic directions provide complementary constraints on past plate positions.

For a geocentric axial dipole with normal-polarity directions expressed northward and downward, tanI=2tanλ relates field inclination to latitude.

The Phanerozoic comprises the Paleozoic, Mesozoic and Cenozoic eras.