Science test 3

Fault

A crack in earths crust

Isotope

Atoms of the same element with different neutrons.

Law of crosscutting isotopes

A rock or fault that cuts through another rock is younger than the rock it cuts.

Intrusion

Magma that enters existing rock.

Eon

The largest unit of geologic time.

Tilting

The slanting of rock layers.

Radioactive Isotope

An unstable atom that releases radiation.

Potassium-argon dating

Dating rocks using potassium and argon.

unconformity

A gap in the geologic record.

Radiocarbon dating

Dating once-living things using carbon-14.

catastrophism

The idea that sudden events shape Earth.

Geologic time scale

A timeline of Earth's history.

Absolute dating

Finding the actual age of rocks or fossils.

Geologic column

A sequence of rock layers.

fossils

Preserved remains or traces of ancient life.

folding

Bending of rock layers.

Uranium-lead dating

Dating rocks using uranium and lead.

Radiometric dating

Dating materials using radioactive decay.

Half-life

Time for half of a radioactive substance to decay.

Radioactive decay

The breakdown of unstable atoms.

James Hutton

Scientist who developed the idea of gradual geologic change.

Geology

The study of Earth.

Index fossils

Fossils used to identify the age of rocks.

What is radioactive dating used for

To determine the age of once-living materials up to about 50,000 years old.

meteorites

Rocks from space that reach Earth.

epochs

Smaller divisions of geologic time.

periods

Divisions of geologic time within eras.

eras

Divisions of geologic time within eons.

precambrian time

The earliest part of Earth's history.

Daughter isotope

The isotope formed when the parent decays.

Parent isotope

The original radioactive isotope.

Uniformitarianism

The idea that the same geological processes occurring today also occurred in the past.