Scientists Review Evidence for the extinction of the Dinosaurs
This ideas in context paper is all about dinsosaurs and it doesnt actually have a predecessor topic to revise. This idea links in with elements of P7 whereby meteors and comets are involved but otherwise there is no prior knowledge.
Before looking through the paper note these definitions so you are clear about what you are reading.
- Meteor: A rock that is headed towards a planet
- Meteorite: A smaller atmospheric rock (A meteor that is inside a planets atmosphere)
- Comet: Composed of rock and ice which follows an elliptical orbit.
- Asteroid: A small rock that orbits the sun.
The main apart about this paper is the evidence of whether the KT mass extinction was caused by an asteroid or Volcanic activity. The first thing I questioned is: what does KT stand for? Well because the event occurred at the boundary between the Cretaceous (K) and Tertiary (T) time periods they have merged it together to call it KT but it is simply the time when all dinosaurs became extinct.
About the Asteroid
- It hit Earth at Chicxulub in Mexico.
- It was 15km wide which is around 10 miles or the size of the Isle of Wight.
- '20 times faster than a speeding bullet' -> 896 * 20 = 17,920 m/s
- 'Only plausible explanation' to destroying marine and land ecosystems very quickly.
- Abundance of Iridium (A lot of it) Iridium is found in asteroids and very rare in Earths Crust.
- Lots of shocked Quartz = shows there was a large force.
About Volcanic Activity
- Volcanoes in Deccan Traps (India)
- There was a series of super volcanic eruptions lasting 1.5 million years
- Spewed 1,100,000km3 basalt lava.
- Cooled atmosphere and caused acid rain globally.
- Evidence for active volcanism
- However only minor changes within 500,000 years before KT extinction
From this there is no real clear cut evidence for either arguement but personally i believe the Asteroid arguement does have more evidence and a better case. This is where the questions would be i would imagine and argue with the evidence presented.
Another part of the Ideas in context is a graph which has got no explanation of how this graph was made such as the evidence it is based upon. The graph shows how frequent asteroids are dependent on the size with an exponential correlation of the larger the size the longer the years between impacts. This would show that an asteroid of the scale argued is very rare however we do not know how reliable the graph is due to not being told any evidence. This is where i believe there will be another question is targeted asking for an interpretation or…