Unit 4 Review

Front

What era do we live in?

Back

Cenozoic

Front

What determines when an era or period begins or ends?

Back

Mass Extinction

Front

What is a fault in geology?

Back

A break in the rock where rock layers slide up or down and no longer line up.

Front

What does the Law of Original Horizontality state?

Back

Sedimentary rock layers are always deposited in flat layers.

Front

What is the half-life of a radioactive substance?

Back

The time it takes for half of the substance to decay.

Front

How much C-14 is left after 1 half-life if you start with 100 grams?

Back

50 grams.

Front

What is the significance of mass extinction events in geology?

Back

They mark the beginning or end of geological eras.

Front

Define 'unconformity' in geology.

Back

A gap in the geological record where rock layers are missing.

Front

What is the Law of Superposition?

Back

In undisturbed sedimentary rock layers, the oldest layers are at the bottom.

Front

What is an intrusion in geology?

Back

Magma that has pushed into existing rock layers and solidified.