Chapter Review: Mountains and Geologic Time

These flashcards cover key terms and concepts from the lecture on mountains and deep time to assist in exam preparation.

Orogens

Elongate, curvilinear belts where mountain ranges occur.

Orogenesis

The process of mountain building.

Deformation

A geologic process involved in orogenesis that alters rocks.

Jointing

The formation of joints, or fractures, in rocks without displacement.

Faulting

Fractures in rock where there has been displacement.

Folding

Bending of rock layers without breaking.

Partial melting

The process where only some minerals in a rock melt into magma.

Foliation

The alignment of mineral grains in a rock, typically due to pressure.

Metamorphism

The alteration of rocks due to temperature and pressure changes.

Glaciation

The process of ice sheet formation and its impact on the Earth's surface.

Erosion

The wearing away and removal of rocks and soil.

Sedimentation

The process of settling or being deposited as sediment.

Bending

A change in the shape of rocks due to deformation.

Breaking

The fracturing of a rock due to stress.

Shortening

The decrease in length of a rock layer.

Stretching

The increase in length of a rock by external forces.

Shearing

The sliding past of one material over another.

Strain

The change in shape resulting from deformation.

Stress

The force applied across a unit area in geology.

Compression

Stress that squeezes materials and results in shortening.

Tension

Stress that pulls apart materials and results in stretching.

Shear stress

Stress that causes surfaces to slide past each other.

Pressure

Equal stress applied from all directions.

Brittle deformation

Fracture of rocks under stress, common in the upper crust.

Ductile deformation

The bending and folding of rocks under stress without breaking.

Anticlines

Arched folds where limbs dip away from the hinge.

Synclines

Trough-like folds where limbs dip toward the hinge.

Monoclines

Step-like folds in otherwise horizontal layers.

Normal faults

Faults where the hanging wall moves down due to tension.

Reverse faults

Faults where the hanging wall moves up due to compression.

Thrust faults

A type of reverse fault with a low-angle dip.

Strike-slip faults

Faults where movement is horizontal, parallel to the fault plane.

Left lateral

Type of strike-slip fault where the opposite block moves left.

Right lateral

Type of strike-slip fault where the opposite block moves right.

Fault scarps

Visible cliffs formed by fault movement.

Brittle faulting

Fracturing, resulting in shattered rock and breccia.

Folds

Bends in rock layers formed by tectonic forces.

Hinge

The line of maximum curvature in a fold.

Limbs

Less curved sections of a fold.

Axial plane

The imaginary plane that divides a fold symmetrically.

Domes

Upward bulging structures exposing older rocks.

Basins

Downward dipping structures exposing younger rocks.

Uplift

Vertical movement of the Earth's surface to higher elevations.

Cratons

Stable continental crust that has not deformed in a billion years.

Shields

Regions of exposed Precambrian igneous and metamorphic rocks.

Platforms

Sedimentary layers covering the Precambrian basement.

Deep time

The vast time scale of geological history.

Relative time methods

Qualitative dating based on the sequence of events.

Numerical time

Quantitative dating providing exact ages.

Volcanic ash

Material used to date geological periods, often millions of years old.

Principle of Uniformitarianism

The concept that present processes are the key to the past.

Sedimentology

The study of how sediments are formed and deposited.

Stratigraphy

The study of rock layers and their historical significance.

Original Horizontality

The principle that sedimentary layers are deposited horizontally.

Superposition

In undisturbed sequences, lower layers are older than upper layers.

Lateral Continuity

Sediment layers extending in all directions until they thin out.

Cross-Cutting Relations

Younger features cut across older features.

Baked Contacts

The baked rock indicates it's older than the igneous rock affecting it.

Inclusions

When a rock contains pieces of another rock, the included rock is older.

Fossil successions

Unique assemblages of fossils indicating geological time periods.

Angular unconformity

Strata deposited over tilted layers; represents missing time.

Disconformity

A gap in the rock record, which represents missing time in parallel strata.

Nonconformity

Sedimentary rocks deposited on older crystalline rocks.

Correlation

Establishing age equivalency of rocks from different locations.

Isotopic dating

Dating based on the decay of isotopes.

Radiocarbon dating

Used for dating more recent organic materials.

Half-life

The time taken for half of a radioactive isotope to decay.

Cenozoic Era

The most recent era in the geological time scale.

Mesozoic Era

The era known for dinosaurs, including the Jurassic period.

Paleozoic Era

An era characterized by early life forms including fish and amphibians.

Geologic Time Scale

Divided into Eons, Eras, Periods, and Epochs based on geological events.

Walther's Law

Facies that occur in vertical successions also appear laterally adjacent.

Geologic maps

Illustrate geological features and structures across varying areas.

Parent-daughter relationship

The decay process from parent isotope to daughter isotope.

Precambrian

The time period before the current geological era.

Tree-ring dating

A method of dating by correlating tree growth rings.