WTG - Chapter 1 Flashcards
- Approximately 4 billion years ago there was a cataclysm, perhaps the most important we know of. What was it and why was it so important?
- Approximately 4 billion years ago the Earth collided with a large object (about the size of Mars) called Thea.
- During the collision Thea disintegrated. Earth was damaged but remained more or less whole.
- Some of Thea’s mass was absorbed by Earth to give it a bigger core.
- This may have given Earth a stronger magnetic field and more solar protection.
- The rest of Thea forms a ‘cloud ‘ of debris around Earth that evenly coalesced to form the Moon.
- A large Moon causes significant tides in the oceans.
- What was the ‘Great Oxidation Event?’
The appearance of significant amounts of oxygen in the Earth’s atmosphere.
- Why was the Great Oxidation Event so important?
As oxygen accumulates in the atmosphere, new opportunities for life to evolve appear; and life does evolve.
However, the more primitive life forms that already exist are now restricted as to where they can live. Oxygen is poisonous to them.
Also, the chemistry of the atmosphere changes with the presence of oxygen an its ability to form other molecules such as CO2.
- What was the Great Dying?
The largest known mass extinction about 250 million years ago at the end of the Permian Period.
This is thought to have been the result of large, sustained volcanic eruptions in what is now Siberia in Russia.
Effusive eruptions (like Hawaii) released large concentrations of CO2. This then changed the nature of the atmosphere and the oceans.
