Tuesday 5/3/11 How the Earth Was Made. Content Objectives 1.We will learn about how scientists have...
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Transcript of Tuesday 5/3/11 How the Earth Was Made. Content Objectives 1.We will learn about how scientists have...
Tuesday 5/3/11
• How the Earth Was Made
Content Objectives
1.We will learn about how scientists have determined the age of the Earth.
2.We will learn about the history of Earth over time.
Language Objectives
1. We will use reading, discussion and writing to learn about the history of Earth.
Schedule
• Agenda, objectives 5 min.• Intro. to geologic methods for
dating rocks 10 min.• Video 25 min.• Discussion 10 min.
How do scientists KNOW things?
• Observations• Experiments• Inferences
Relative Dating (this rock is older than that rock)
• Most of the time the rocks on the top are older than the rocks on the bottom
Absolute Dating(this rock is 28 million years old)
• Some atoms are not stable—they break down into “daughter” atoms
• Ex.: Uranium changes into a form of lead at a constant known rate
Oldest Rock
• Oldest rocks on Earth are the Acasta Gniess of northern Canada • 4.03 billion years old
© NASA
Acasta Gneiss
Zircon mineral
Oldest Zircon Grain
4.4 byzircon grain
www.geology.wisc.edu/zircon/Earliest%20Piece/Images/2a-team.jpg
© NASA
• Ancient mineral grain found at Jack Hills, Australia • Mineral grain eroded from first crust and then deposited in a new rock
• Dates the Earth’s first crust to around 4.4 billion years
Meteorites
• Radiometric age of meteorites date the formation of the Solar System and Earth (4.55 billion years old)
en.wikipedia.org/wiki/Image:Canyon-diablo-meteorite.jpg
http://upload.wikimedia.org/wikipedia/commons/0/00/Crab_Nebula.jpg
Crab Nebula
Canyon Diablo meteorite