Geologic and Biologic Scaled Time-Line

Geologic and Biologic Scaled Time-Line Integrated Science 2 Name: Date: Pd:  Background The Earth solidified 4.6 billion years ago. Life has been evolving on Earth for more than 3.5 billion years. These are time spans that are difficult to comprehend. Our limited experience with time involves years grouped into decades and centuries – not millions or billions of years! To understand geologic and biologic origins we can try to represent time concretely by converting time into a linear dimension with a scale that is more manageable. Scaled time lines can be used to represent changes in a more usable context. In this activity, you will construct a scale model of the major geologic and biologic events in Earth’s history. This will help give you a sense of when critical events happened in the history of life and of the earth.

 Pre-Lab Questions

1. On a timeline of the Earth’s history, put an “X” where you think the age of dinosaurs would first appear.

< Earth Formed Present Day >

2. On a timeline of the Earth’s history, put an “X” where you think humans would first appear.

3. On a timeline of Earth’s history, put an “X” where you think the continents formed.

 Procedures Remember: 109 = 1,000,000,000 one billion 106 = 1,000,000 one million 105 = 100,000 one hundred thousand 104 = 10,000 ten thousand

1. Review the data tables that accompany this activity. You will notice that the “Distance on Timeline (centimeters)” column is blank. This must be filled in before you can begin creating your scaled model. 2. a.) Your model will be 11 meters. This distance equals 1,100 cm. Therefore, every meter of space on your timeline is equal to 420 million years. ] b.) To begin you must convert the data found in the “Approximate Age” column to a unit of distance. The formula for this conversion is as follows:

c. ) Subtract your “Distance From Present” from 11 to find out where you will stop and plant your flag. Record this value in the “Distance on Timeline” column in your data table. Example: the third conversion on the Geologic Time Scale (first Single-celled organism) requires you to convert 4000 million years to distance. Using the formula above the conversion would look like this:

therefore, you would plant your flag 1 meter and 48 centimeters from the beginning to represent the point where the first single-celled organisms appeared.

 Data Table

Event Approximate Age Distance in Classroom (cm) A Formation of the Earth 4600 million years B Oldest known rock 4300 million years C First single-celled organism 4000 million years D Age of most continental crust 3700 million years E First viruses appear 3500 million years Blue-green algae F 3000 million years (First oxygen-producers) G First fungi appear 1000 million years H First multi-celled organism 700 million years Precambrian Extinction I 650 million years (70% of all life wiped out) J First shellfish appear 570 million years K First fish appear 510 million years L First true plants appear 498 million years M First sharks appear 390 million years N First amphibian appear 375 million years O First reptile appears 325 million years Permian-Triassic Extinction P 250 million years (99% of all life wiped out) Mesozoic Era begins Q 245 million years (Age of the dinosaurs) R First mammal appears 200 million years S Age of most oceanic crust 180 million years T First known bird appears 160 million years U Rocky Mountains formed 80 million years V Extinction of the dinosaurs 65 million years W First proto-humans appear 3.5 million years X Earliest modern humans appear 2 million years Y Last Ice Age 0.02 million years Z Recorded human history begins 0.01 million years

2 Analysis Questions 1. Revisit your pre-lab questions. How close were you to predicting the timing of each event? Which one were you closest to?

2. Which event’s position on the timeline was the most surprising to you? Why? (what preconceived notions did you have about this event?)

3. How many events involving living organisms are in the first half of earth’s history?

How many events involving living organisms are in the second half of earth’s history?

4. How long did dinosaurs exist on earth?

How long have humans (including proto-humans) lived on earth?

5. Which organisms would have gone extinct at the Permian-Triassic extinction 250 million years ago?

6. For how many billions of years, did earth exist with nothing more sophisticated than single-celled organisms?

What percent of earth’s history is this? (divide your answer by 4.6 and multiply by 100).

3 Scaled Time Line 7. Using your data table, create a timeline below organism evolution from single-celled organisms to modern humans by listing them in order of appearance on earth (you may want to turn your paper sideways)

4 Formation of the Earth A. 4.6 Billion Years Ago

Oldest Known Rock B. 4.3 Billion Years Ago

5 Scaled Time Line 6 First Single-Celled C. Organism 4 Billion Years Ago

Age of Most Continental D. Crust 3.7 Billion Years

7 Scaled Time Line First Viruses Appear E. 3.5 Billion Years Ago

Blue-Green Algae F. (First oxygen-producers) 3 Billion Years Ago

8 First Fungi Appear G. 1 Billion Years Ago

First Multi-Celled H. Organisms 700 Million Years Ago

9 Scaled Time Line Precambrian Extinction I. (70% of all life wiped out) 650 Million Years Ago

First Shellfish Appear J. 570 Million Years Ago

10 First Fish Appear K. 510 Million Years Ago

First True Plants Appear L. 498 Million Years Ago

11 Scaled Time Line First Sharks Appear M. 390 Million Years Ago

First Amphibian Appears N. 375 Million Years Ago

12 First Reptile Appears O. 325 Million Years Ago

P. Permian-Triassic Extinction (99% of all life wiped out)

13 Scaled Time Line 250 Million Years Ago

Mesozoic Era Begins Q. (The Age of the Dinosaurs) 245 Million Years Ago

First Mammal Appears R. 200 Million Years Ago 14 Age of Most Oceanic Crust S. 180 Million Years

T. First Known Bird Appears

15 Scaled Time Line 160 Million Years Ago

Rocky Mountains Formed U. 80 Million Years Ago

16 Extinction of the Dinosaurs V. 65 Million Years Ago

First Proto-Humans W. Appear 3.5 Million Years Ago

17 Scaled Time Line Earliest Modern Humans X. Appear 2 Million Years Ago

Last Ice Age Y. 20 Thousand Years Ago

18 Recorded Human History Z. Beings 10 Thousand Years Ago

19 Scaled Time Line