Mass Extinctions Flashcards
1
Q
What are a mass extinction
A
A mass extinction is when the massive numbers if species all over the world die simultaneously
2
Q
The five mass extinctions:
A
O D then P our T he C ocaine
Ordovician Devonian Perm Triassic Cretaceous
3
Q
The sixth extinction
A
- This extinction is caused by man
2, this extinction is much faster than any previous extinction
4
Q
Intrinsic factors
A
(Intrinsic factors were present on earth)
- Volcanic eruptions
- Continental drift
- Ice ages
5
Q
Volcanic eruptions
A
- The ash and dust hung in a dense cloud over the earth and blocked the rays of the sun. This caused a cooling of the earth and photosynthesis could not take place
- Sulphur dioxide fell to earth as acid rain
- Carbon dioxide caused a greenhouse effect and global warming increased once the dust settled
6
Q
Continental drift
A
It possibly led to:
- Increased competitions
- Changes in abiotic conditions
- Increased volcanic activity
7
Q
Ice ages
A
The effects were:
- Lower sea levels because water was trapped in ice caps… habitats of marine species decreased
- Species were forced to migrate north to the equator
- Less water is available causing the death of those species unable to adapt
8
Q
Extrinsic factors
A
Extrinsic factors came from outside the earth. Large meteorites hit the earth and these meteorite collisions contributed to extinctions
9
Q
What happens when a meteorite hits the earth
A
- Large amounts of dust sand and gases are thrown into the air and block sunlight, photosynthesis cannot take place sufficiently
- Sulphuric acid in the air forms acid rain and falls on the earth
- Causes the earth to cool down
- The lower temperatures were very problematic to dinosaurs because they couldn’t control their own body temperature
- Fires spread over the earth
10
Q
Evidence for the meteorite collision theory
A
- Large amounts of iridium in rock layers of this period
2. An impact crater about 10km in diameter and about 65 million years old was found in the sea in Mexico
