Flashcards in The Evolution of the Atmosphere Deck (18):
What the 3 phases of the evolution of the atmosphere?
1. Volcanoes gave out gases
2. Green plants and algae evolved and gave out oxygen
3. Ozone layer allows evolution of complex animals
What state was the Earth's surface originally and for many millions of years?
What did the high heat of the Earth mean for the atmosphere?
Any atmosphere just 'boiled away' into space
What eventually happened in the 1st phase?
The Earth began to cool a bit and a THIN CRUST formed, BUT volcanoes kept erupting
How do we think the oceans and atmosphere were formed?
Volcanoes erupted and gave out lots of gas
Name the 5 substances that were probably in the early atmosphere and how abundant they were.
1. CO2 - majority of atmosphere
2. Oxygen - virtually nothing
3. Water vapour - may have been there
4. Methane - small amount
5. Ammonia - small amount
What was the Earth's early atmosphere probably similar to?
The atmospheres of Mars and Venus today
How do we think oceans were formed?
When the water vapour CONDENSED
In phase 2 what were the first organisms to form?
1. Green plants
Why were green plants and algae the 1st organisms to evolve on Earth?
They thrived in the high CO2 atmosphere
Where did the CO2 the early atmosphere go? (2) how much each?
1. Dissolved into the oceans - most
2. Absorbed by green plants and algae - some
Where did O2 come from?
Produced by green plants and algae by photosynthesis
What happened to the early green plants and algae?
They died and got buried under layers of sediment
What else was buried under layers of sediment?
The skeletons and shells of marine organisms that had slowly evolved
What happened to the carbon and hydrocarbons inside the skeletons and shells of the marine organisms?
They became 'locked-up' in SEDIMENTARY ROCKS as INSOLUBLE COMPOUNDS (e.g. limestone) and FOSSIL FUELS
What happens when we burn hydrocarbons today?
The 'locked-up' carbon s released and the concentration of CO2 in the atmosphere rises
What did the build up of oxygen in the atmosphere do to life on Earth? (2)
1. Killed off organisms that couldn't tolerate it
2. Allowed other, more COMPLEX organisms to evolve and flourish