Dating Rocks
The time for half (1/2) of a "parent" atom to change.
What is a half-life?
These tiny bacteria made the first oxygen using photosynthesis.
(What are) Cyanobacteria?
The Late Heavy Bombardment was when asteroids and these icy objects hit Earth.
(What are) Comets?
The early solar system was messy and dangerous. (The opposite of stable).
(What is) Unstable?
The big idea: Life changes Earth, and Earth changes life. They change together. (Hint: Co- means together).
(What is) Coevolution?
This is used to date new things (like mummies). It has a short half-life.
What is Carbon-14?
Layers of iron (like rust) at the bottom of the ocean. This shows oxygen was in the water.
(What are) Banded Iron Formations (BIFs)?
The Late Heavy Bombardment happened when these two gas giant planets moved. (Hint: The two biggest planets).
(What are) Jupiter and Saturn?
Today, planets have safe, stable orbits that are shaped like circles.
(What are) Circular orbits?
The first tiny life (bacteria) appeared about 3.5 billion years ago.
(What is) First life?
This is used to date very old rocks. It has a long half-life.
What is Uranium-238?
Red-colored rocks on land. This shows oxygen was in the air.
(What are) Red beds?
The asteroids and comets brought this important liquid to Earth, which made the oceans.
(What is) Water?
Planets with oval (elliptical) orbits have big changes in their weather and temperature.
(What is) Climate?
In one extinction, this supercontinent (all land together) moved to the South Pole.
(What is) Gondwana?
The process of finding the real age of rocks. (It's the category name!)
What is radiometric dating?
Oxygen was poison to the first simple life. Another word for poison.
(What is) Toxic?
A ratio (like a chemical signature) used to check if asteroid water matches Earth's water. (Hint: D/H)
(What is) the D/H ratio?
A stable, safe orbit allowed Earth to have liquid water and life. (Two answers!)
(What are) Liquid water and life?
In the Devonian extinction, new land plants caused "food" (nutrients) to wash into the ocean.
(What are) Nutrients (or nutrient runoff)?
Scientists dated Moon rocks and these special crystals to find the age of the solar system.
What are zircon crystals?
The GOE (Great Oxygenation Event) happened about this many billion years ago. (Hint: 2.5)
(What is) 2.5 billion years ago (bya)?
We know the Late Heavy Bombardment happened because we see these big holes on the Moon.
(What are) Craters?
The solar system became stable after this big event with many asteroid hits. (Hint: Category 3 name).
(What is) the Late Heavy Bombardment (LHB)?
When all of a type of animal or plant dies forever.
(What is) Extinction?