Geologic history test review

What is the name of the longest period of time before the eras?

Precambrian

list the importants of earths development

1. earth forms

2. first life

3. formation of oxygen atomosphere

4. fossil fuel formation

5. pangea extinction

6. dinosaur extinction

7. first man

8. pleistocene ice age

What separates the three main eras of geological time?

Mass extinction

What is the main form of life in the Paleozoic era?

Amphibians

What is the main form of life in the Mesozoic era?

Reptiles

What is the main form of life in the Cenozoic era?

Mammals

What does relative dating tell us?

Which rock layer is older

What does absolute dating tell us?

The actual age of the rock

How is igneous rock formed?

Magma cools and hardens

How is sedimentary rock formed?

Rocks weather, erode, and get deposited

How is metamorphic rock formed?

By adding heat and pressure

What law tells you what is older among sedimentary rock layers?

Law of superposition

What is a fault?

A break or crack in Earth's crust along with the rocks shifting their position

What is a fold?

A bend in the rock

What does tilting refer to in geology?

When the layers become angled instead of flat

What law determines the age of a fault or intrusion compared to surrounding rocks?

The law of crosscutting

What does it mean when an element is radioactive?

It is unstable and would like to decay into a stable daughter isotope

What is half-life?

Time it takes for half of the unstable isotope to become a stable isotope

What isotopes do you compare to determine the age of rocks?

The amount of parent and daughter isotopes

What method do we use Carbon-14 to date?

Things that are up to 70,000 years old

What type of rock is used for radiometric dating?

Igneous

In which type of rock would you find most fossils?

Sedimentary

What makes a good index fossil?

An organism that lived for a short period of time and over a large geographic area.