Geologic Time Our Planets History Geologic time is

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Geologic Time

Geologic Time

Our Planet’s History • Geologic time is the time frame of our planet’s history.

Our Planet’s History • Geologic time is the time frame of our planet’s history. • While 30, 000 year old cave paintings seem really old to us when compared to modern art, this is a miniscule amount of time in comparison to the age of our planet. • Earth has been in existence for 4, 600, 000 years. 4. 6 billion years!

How do Scientists Know the Earth’s Age? • When scientists discovered radioactivity, they were

How do Scientists Know the Earth’s Age? • When scientists discovered radioactivity, they were able to develop radiometric dating methods to determine the age of ancient rocks. • The consistency of the results gives scientists confidence that the ages are correct to within a few percent. • Ancient rocks exceeding 3. 5 billion years in age have been found on all of Earth's continents.

4, 600, 000 years includes… • The birth of our planet • Evolution of

4, 600, 000 years includes… • The birth of our planet • Evolution of the first single-celled life-forms • Assembly of at least three supercontinents (Rodinia, Pannotia, and Pangaea) • The rise and fall of dinosaurs • The colonization and dominance of flowering plants When did humans first appear?

 • Modern Cro-Magnon humans showed up less than 50, 000 years ago. •

• Modern Cro-Magnon humans showed up less than 50, 000 years ago. • Understanding the true meaning and scale of Geologic Time can be challenging, so today we are going to do two activities to help you put Geologic Time in perspective.

Activity #1: Clapping the Earth’s Life • Let’s represent one decade (10 years) in

Activity #1: Clapping the Earth’s Life • Let’s represent one decade (10 years) in seconds. • Each year will be represented by one second which equals one clap of the hands. 1 clap = 1 second = 1 year • How long does it take to clap your age? • If your grandmother is 70, how long will it take to clap her age?

How long would it take to clap the age of this 100 -year-old tortoise

How long would it take to clap the age of this 100 -year-old tortoise in… seconds? _____ minutes? _________ (Remember: there are 60 seconds per minute)

How long would it take in minutes… • To clap the age of the

How long would it take in minutes… • To clap the age of the 234 -year-old Declaration of Independence? 234 seconds 60 sec/min = _____min • To clap the age of the Great Pyramid of Egypt built 4571 years ago? 4571 seconds 60 sec/min = _____ min

How long would it take to clap the Earth’s Age, 4. 6 billion years?

How long would it take to clap the Earth’s Age, 4. 6 billion years? • Do you think you could clap the Earth’s Age in your own lifetime? Circle one. YES NO

The Calculation… • There are 60 seconds per minute • 60 sec/min X 60

The Calculation… • There are 60 seconds per minute • 60 sec/min X 60 min/hr = 3, 600 sec/hr • 3, 600 sec/hr X 24 hrs/day = 86, 400 sec/day • 86, 400 sec/day X 365. 25 days/year = 31, 557, 600 sec/year • How long will it take to clap 4, 600, 000 seconds? • 4, 600, 000 seconds 31, 600, 000

 • 4, 600, 000 seconds 31, 600, 000 seconds/year = • That’s almost

• 4, 600, 000 seconds 31, 600, 000 seconds/year = • That’s almost 145 years! • Remember, your own lifetime can be clapped in less than 15 seconds!

Activity #2: TP Timeline • Now we are going to make a TP Timeline!

Activity #2: TP Timeline • Now we are going to make a TP Timeline! • The tissue we’re using contains 176 sheets per roll. • The entire roll represents the earth’s lifetime, so we need to figure out how many years each square sheet of tissue will represent. 4, 600, 000 176 sheets = 26 million years/sheet

Major Earth Events • We are going to label the tissue timeline to mark

Major Earth Events • We are going to label the tissue timeline to mark significant events in the Earth’s history. • We’ll start from today and work backward in time.

 • • • TP Timeline Early modern humans – 130, 000 years ago.

• • • TP Timeline Early modern humans – 130, 000 years ago. That’s 0. 5% of one sheet from today (the edge of the first sheet) The first hominids – 7, 000 years ago 27% of one sheet from today Many dinosaurs go extinct – 65, 000 years ago. 2. 5 sheets from today First bird fossils formed – 174, 000 years ago. 6. 7 sheets from today “The Great Dying” – 245, 000 years ago 9. 4 sheets from today First fish, first insects – 490, 000 years ago 18. 8 sheets from today

 • Abundant shell life = 542, 000 years ago 21 sheets from today

• Abundant shell life = 542, 000 years ago 21 sheets from today • Oxygen occurs in Earth’s atmosphere – 2, 000, 000 years ago. 76 sheets from today • First life forms (prokaryotes) – 3, 600, 000 years ago 138 sheets from today • Oldest rocks on Earth – 4, 000, 000 years ago. 154 sheets from today (22 sheets from the Earth’s origin) • Formation of Earth – 4, 600, 000 years ago end of the roll of paper!

Reflection • Complete an exit slip answering the following prompts: – Today I learned

Reflection • Complete an exit slip answering the following prompts: – Today I learned for the first time that… – This makes me think about… – Now I am curious to know…