C1.7 - Changes In The Earth And Its Atmosphere Flashcards
What occurs in the core to produce heat?
Radioactive decay.
What causes convection currents in the mantle?
Heat from radioactive decay.
What are the three layers of the earth?
The crust, the mantle and the core.
What causes tectonic plates to move?
Convection currents.
What causes earthquakes and volcanic eruptions?
Sudden movements at the boundaries between two plates.
Why are earthquakes/volcanic eruptions difficult to predict?
Plates move suddenly.
What was the earth’s early atmosphere predominantly made from?
Carbon dioxide.
What are the differences in gases between the modern and prehistoric earth’s atmosphere and why? (2)
- There is less carbon dioxide because it has been dissolved in oceans and absorbed during photosynthesis.
- There is more oxygen as a result of photosynthesis.
What are the relative percentages of gases in our atmosphere?
78% nitrogen, 21% oxygen and small amounts of other gases such as carbon dioxide and argon.
What are the three phases of the atmosphere?
- Volcanoes have out gases.
- Green plants evolved and produced oxygen.
- The ozone layer allowed complex animals to evolve.
What is the Earth’s core made from?
Iron and nickel.
What occurs in the core to produce heat?
Radioactive decay.
What causes convection currents in the mantle?
Heat from radioactive decay.
What are the three layers of the earth?
The crust, the mantle and the core.
What causes tectonic plates to move?
Convection currents.
