Unit 3 Earths History

Front

What is a fossil?

Back

The remains of a prehistoric organism.

Front

What does the law of uniformitarianism state?

Back

The idea that the earth has always changed in uniform ways.

Front

What is extrusive igneous rock?

Back

Rock produced when magma exits and cools as lava at or near the earth's surface.

Front

What is an unconformity?

Back

A break in time otherwise continuous rock record.

Front

What is a mold fossil?

Back

A fossilized imprint made in the substrate.

Front

What is a trace fossil?

Back

A fossil that provides evidence of the activity of ancient organisms.

Front

What is an index fossil?

Back

A fossil that is used to define and identify a particular time period.

Front

What is the process of sea floor spreading?

Back

The process by which new oceanic crust is formed at mid-ocean ridges and older crust is pushed away.

Front

What is Pangaea?

Back

A supercontinent that existed during the late Paleozoic and early Mesozoic eras.

Front

What is a petrified fossil?

Back

A fossil formed when organic material is replaced with minerals.