Earth Structure and Atmosphere Flashcards
What was the old explanation for fossils on opposite sides of the Atlantic Ocean?
Land bridges that have been covered since.
What was the evidence that Alfred Wegener noticed?
- Continental coastlines fit together
- Matching layers of rocks in different continents
- Fossils in the wrong places (e.g tropical plants in Arctic islands)
What was Wegener’s theory called?
Continental Drift.
Why wasn’t Wegener’s theory accepted?
He couldn’t explain why the continents were moving
or
There wasn’t enough/any evidence
Why is the mantle hot?
Radioactive decay.
Why does the mantle flow?
Convection currents, from the heat of radioactive decay.
What is the core of the Earth made of?
Iron and nickel.
What is the top layer of the earth?
The crust.
What often occurs at the boundaries of two plates?
Volcanoes and earthquakes.
What are earthquakes caused by?
Sudden movement of tectonic plates.
Why are earthquakes impossible to predict?
Tectonic plates move suddenly.
Why was there no atmosphere on early Earth?
The Earth’s surface was molten, so any atmosphere boiled away.
Where did the early atmosphere come from?
Volcanoes.
What was the early atmosphere made up of?
Mostly CO2, some water vapour, and small amounts of methane and ammonia.
How were the oceans formed?
Water vapour condensation.
Why did CO2 levels drop in the early atmosphere?
- Green plants and algae took in CO2 for photosynthesis
2. CO2 dissolved in the oceans
What is locked-up carbon?
Carbon trapped in sedimentary rocks as insoluble carbonates and fossil fuels.
What were early organisms killed off by?
Oxygen build up in the atmosphere.
What did the oxygen build up in the atmosphere cause?
- Ozone layer
2. Development of more complex organisms
What gases were in the Earth’s atmosphere, according to the primordial soup theory?
Nitrogen, hydrogen, ammonia and methane.
What was the trigger of chemical reactions to create primordial soup?
Lightning.
Why was the Miller-Urey experiment not completely successful?
They only used gases that they thought were in the atmosphere.
What is air fractionally distilled for?
Industry.
How is air fractionally distilled?
- Air cooled to about -200C
- Heated slowly
- Gases separated by fractionating column
