The principle that states that all geologic change occurs suddenly.

Younger rocks lie above older rocks, if layers are left undisturbed.

Faults or intrusions are younger than any layer of rock they cut through.

The trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock.

All fossils discovered on Earth.

The weather conditions in an area over a long period of time.

A long cylinder of ice obtained from drilling through ice caps or ice sheets; used to study past climates.

Any method of determining whether an event or object is older or younger than other events or objects.

Any method of measuring the age of an event or object in years.

A method of determining the absolute age of an object by comparing the amount of parent isotope vs. daughter isotope and using half-life.

An ordered arrangement of rock layers that is based on the relative ages of the rocks (older rocks are at the bottom).

Isotope that is unstable and decays; also called a parent isotope.

The process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element.

Isotope that is unstable and decays; also called a radioactive isotope.

Stable isotope that forms after the parent isotope decays.

The time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope.

Fossils that are used to estimate the absolute age of the rock layers in which they are found. These organisms must have lived during a short time span, have unique features, and be common over large areas.

The scientific study of the origin, history, and structure of Earth and the processes that shape Earth.

The standard method used to divide Earth's long natural history into manageable intervals of time.

Preserved remains or evidence of ancient living things

Fossil Preservation: Minerals in groundwater fill in the pore spaces of dead organisms

Principle that in undisturbed rock layers, the oldest rocks are on the bottom

The numerical age, in years, of a rock or object

The process by which an unstable element naturally changes into another element that is stable

Geological Timeline: Longest amounts of time, broken into eras

Geological Timeline: These are broken into periods

Geological Timeline: These are broken into epochs

Geological Timeline: These are broken into epochs

The Earth is estimated to be approximately:

Earth's core is made up of:

When the Earth was young, it was molten do to high amounts of energy and heat from:

The oldest rocks found on Earth are approximately:

Why is it hard to find very old rocks on Earth?

The first particles that formed the Earth were drawn together from:

Once the Earth began to accumulate more mass, which force was responsible for its continued growth?

The moon probably formed when a small planet-sized object rammed into Earth. What evidence supports this theory?

Scientists are able to determine how the Earth formed by (choose all that apply):

TRUE or FALSE: The Earth is shaped like a perfect sphere.

In the earliest stages of Earth's development, our planet was made of what?

In the second phase of Earth's development, what happens?

A nebula is a

What happens during a supernova?