Plate Tectonics and Geologic Time Flashcards

Vocabulary flashcards covering Earth Science topics including Plate Tectonics, Geologic Structures, and the Geologic Time Scale.

Earthquake

Occurs because of the force/stress happening in rocks.

Diastrophism

Dynamic internal forces that causes earth’s surface deformation.

Tectonic movement

Creates tremendous stress near plate boundaries that deforms rocks.

Continental Crust

Holds the continents; less dense than oceanic crust because of older materials like silica and aluminum-based granite.

Lithosphere

Rigid, brittle materials composed of the crust and upper mantle whose molten peridotite composition allows it to resist flow.

Asthenosphere

Found in the mantle; contains all the liquid and semi-liquid rock and behaves in a plastic manner.

Oceanic Crust

Denser, thinner, and younger crust formed at the bottom of the oceans due to petrogenic processes; composed of silica and magnesia-based basalt.

Divergent Boundary

Stretching of adjacent rock producing normal faults and grabens; contains rift zones where continents stretch and break apart.

Convergent Boundary

Compression that produces large regions of folds and reverse faults; involves subduction where plates collapse and volcanic arcs are made.

Transform Boundary

Friction holds rock together as plates gradually slip past each other, creating stress that may fold, fault, and uplift nearby rocks.

Mantle convection

The thermodynamic heating of the liquid rocks in the mantle that provides movement to the tectonic plates.

Slab pull

Tensional force exerted by cold, dense oceanic plates as they subduct into the mantle due to their weight.

Ridge push

Also known as gravitational sliding; a driving force occurring at mid-ocean ridges as the lithosphere slides down the asthenosphere.

Ductile deformation

A process where rocks bend without breaking, forming folds.

Brittle deformation

A process where rocks break, forming joints or faults.

Anticline

A fold arching upward, commonly caused by compressive stress, forming a saddle between two peaks.

Syncline

A U-shaped fold arching downward in which strata dip towards the fold axis.

Monocline

An open, step-like structure where layers are all inclined in the same direction on either side of the fold axis.

Slip

The distance that rocks on opposite sides of a fault have moved.

Normal fault

Forms where tectonic movement stretches Earth’s crust, pulling it apart due to tensional stress.

Reverse fault

Fractured rock created by compressive forces that push rock together and break it.

Strike-slip fault

Vertical fractures where rocks on opposite sides move horizontally past each other due to shear stress.

Joints

A fracture in which rocks on either side have not moved; these are planes of weakness in otherwise strong rock.

Elasticity

A temporary change in the physical structure of a rock.

Brittleness

A property characterized by high strength but low toughness.

Geologic Time Scale

A system that distinguishes Earth's history based on life-forms that existed at certain times since the planet's formation.

Fossils

The remains or evidence of an organism from the geologic past preserved in silt or rock.

Stratigraphic

The ordering and analysis of Earth's layers (strata) based on chronological dating techniques and relative positions.

Epoch

A subdivision of a period in geological time lasting around several million years.

Period

The basic unit of geological time lasting $10$ million of years during which a specific kind of rock system is produced.

Era

A subdivision of an eon scaling hundreds of millions of years where periods are compacted together based on characteristics.

Eon

Large divisions of geological time; the Phanerozoic is the current eon.

Precambrian Supereon

The longest part of Earth's history comprising at least $88\%$ of Earth's absolute time.

Hadean

An eon within the Precambrian Supereon described as 'burning Earth.'

Archaean

An eon within the Precambrian Supereon marking the first rain and birth of early extremophiles.

Proterozoic

An eon within the Precambrian Supereon marking the boom of life all over Earth.

Paleozoic Era

Commonly known as the 'age of invertebrates'; the longest era in the Phanerozoic eon.

Mesozoic Era

Commonly known as the 'age of reptiles.'

Cenozoic Era

Commonly known as the 'age of mammals.'

Unconformity

A missing part, layer, or strata in the geologic record.

Radioactive decay

The process where atoms or molecules continually emit energy to achieve stability.

Isotope

A variance of an element due to an increase of neutrons.

Parent Isotope

The initial isotope that undergoes radioactive decay.