Definitions
Geologic Time Scale
Grab Bag
Divisions of Geologic Time
Fossils
100
_________ is the death of every member of a species
What is extinction?
100
Name the time in Earth's history: Clue #1: 4.6 billion to 542 million years ago Clue #2: no Oxygen in air
What is Precambrian?
100
True/False: Humans have existed for most of Earth’s history.
False.
100
The largest division of geologic time are ______________.
What are eons?
100
How did scientists know what dinosaurs looked like?
They examine fossil evidence.
200
___________ is the extinction of many species at the same time
What is mass extinction?
200

Name the time in Earth's history: Clue #1: 251 million years ago Clue #2: Age of Reptiles Clue  #3 ended by asteroid colliding with Earth

What is the Mesozoic era?

200
How is the geologic time scale of Earth’s history divided?
by major events or changes.
200
Eons are divided into __________.
What are eras?
200
The earliest fossils are of …
One-celled organisms
300
The age of an event or object in relation to other events or objects is called ______________
What is Relative age
300

Name the time in Earth's history: Clue #1: 65 million years ago up until today Clue #2: fossils are in the top layer

What is the Cenozoic era?

300
True/False: Throughout Earth’s history, the number and type of life forms has remained fairly constant.
False.
300
Eras are divided into __________.
What are periods?
300
A fossil is an object that contains traces, remains, or evidence of ..
Living things from long ago
400

This states that the oldest layers of rock are at the bottom and that layers get newer as you reach the top?

What is the Law of Superposition

400

Name the time in Earth's history: Clue #1: Humans first appeared

What is the age of mammals?

Cenozoic Era

400

Earth is approximately how old?

4.6 billion years

400
Periods are divided into ____________.
What are epochs?
400
A well-known fossil group of extinct marine creatures that first appeared in the early Cambrian period.
What is the trilobite?
500

The law of croscutting states that the diagonal layers that cut through sedimentary rock are __________ than the horizontal layers that they cut through

What is younger?

500

The first trace of life on earth can be traced back to how many billions of years ago?

3.8 billion years ago.

500

What is it called when a layer of sedimentary rock is missing from the fossil record?

What is an uncomformity?

500
There are _____ eons in Earth’s history.
What is four?
500

What are the characteristics that make a good index fossil?

only found in one layer/found in many different areas

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