The preserved remains or traces of an organism that lived in the past

The timeline developed by scientists of the major events and the changes in life during the earth's history

Millions of fossils that have been collected and studied, paint a picture of life in the past.

When an entire species dies out.

The study of earth's past

Fossils from organisms that only lived during a short period of Earth's history. Many fossils of this organism can be found over wide area of Earth.

A key example of an organism used as an index fossil. A hard shelled animal whose body had three section, lived in shallow seas and became extinct during the mass extinction that ended the paleozoic era.

In undisturbed rock layers. The layers on bottom are older than the layers above it.

The age of an object compared to another. Uses terms like older and younger. Is not a number!

Finding the relative age of something like rock layers

Finding EXACTLY how old something is in years.

Finding the absolute age of something.

Using the decay rate of radiometric atoms to date rocks and fossils.

A type of radiometric dating used to date things that used to be alive.

The amount of time it takes for half of the parent atoms to decay into daughter atoms during radiometric dating.

The radioactive atom that decays into the daughter atom during radiometric dating.

The atom that results from the decay of the radioactive parent atom during radiometric dating.

Precambrian

Paleozoic Era

Mesozoic Era

Cenozoic Era

Forms when sediments bury and organism, changes into rock, the organism decays leaving a cavity the shape of the organism

Forms when minerals soak into the buried remains, replacing the remains, and changing them into rock.

Forms when a mold is filled with sand or mud that hardens into the shape of the organism.

When entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar or amber.

Forms when an organism or parts, like leaves, steps, floweres or fish are pressed between layers of soft mud or clay that hardens squeezing almost all the decaying organism away leaving the carbon imprint in the rock

Forms when mud or sand hardens to stone where a footprint, train or burrow of an organism was left behind. Not part of the organism itself.

the assumption that the same natural laws and processes that operate in the universe now have always operated in the universe in the past and apply everywhere in the universe.

A type of fault where one plate moves up and the other moves down

A type of fault where the two plates slide past each other on a horizontal plane

The broken pieces of earth's crust which are moving slowly on top of the mantal

A break in the rocks that make up earth's crust.

Type of rock that can be used for radiometric dating.

Type of rocks that contain fossils

These cylinders of ice that are drilled out of glaciers and polar ice sheets, tell us about how the climate has changed over time.