Past Organisms
Timeline
Divisions of Time
How old are you?
All the other fun things.
100
Traces or remains of a once living thing that has been preserved.
What is a fossil?
100
Earliest fish appeared during this era.
What is the Paleozoic
100
The largest division of geologic time.
What is an eon?
100
When age compared with ages of other rocks and can only show which rocks are older or younger.
What is relative dating?
100
A super continent that formed when all the land masses on Earth combined about 250 mya.
What is Pangea?
200
A scientist that studies, collects, and classifies fossil.
What is a paleontologist?
200
Geologic time begins with a long span of time which covers about 88 percent of Earth’s history and ended about 544 million years ago.
What is the Precambrian Eon?
200
Periods can be divided into this.
What is an epoch?
200
Determines the age of rocks and other objects in years
What is absolute dating?
200
The cross section below shows undisturbed sedimentary bedrock. The ages of various layers are indicated, and reference points within the rocks are labeled A through D.
The remains of an early dinosaur could be found at reference point...
What is A
300
What do we call fossil from organisms that only existed in a short period of time. These fossils are used to help find the relative age of rock layers.
What is index fossil
300
Many modern groups of mammals are in this era.
What is the Cenozoic era?
300
Two or more periods make up this.
What is an era?
300
In horizontal sedimentary rock layers the oldest layer is at the bottom; each layer higher is younger than the layer below it.
What is the law of superposition?
300
A ___________ is the time required for half of the atoms of a radioactive element to decay
Half Life
400
A type of fossil that is preserved evidence of life or other events.
What is a trace fossil?
400
Earliest birds appeared in this period.
What is the Jurassic?
400
Two or more eras make up this.
What is an eon?
400
What % of a radioactive element would remain after 2 half-lives?
What is a What is 25%
400
The end of the Paleozoic Era ended because of this.
What is the Permian Mass Extinction?
500
Name one requirement that causes a fossil to form.
What is protection from scavengers, quickly buried, hard parts like, bones, shells, and stems, rock layer are undisturbed?
500
A gap in the geologic record formed when sedimentary rocks cover an eroded surface is called a(n)
What is an unconformity
500
This is how the geologic time scale is organized.
What is major events in Earth's history?
500
Elements occur naturally in the environment and they break down and change into another element.
What is radioactive decay?
500
Advance and retreat of last continental ice happened in this period.
What is Quaternary