Did an Asteroid Impact Cause Dinosaur Extinction?

1. Did an Asteroid Impact Cause Dinosaur Extinction? By Justin Howenstine

2. Could an impact cause Extinction? • 2 Theories of how an impact could cause dinosaur extinction • Global Firestorm • Long term environmental effects • Supporting Evidence

3. Global Firestorm • How does an impact cause a firestorm? • When planet is impacted by such a massive asteroid shock waves reverberate through the planet’s surface • The shock waves shake the oceans and rupture pockets of methane that are trapped under gas hydrates • Also ‘slumping’ or a sliding down of the ocean bottom occurs which releases methane

4. Firestorm • Barton Hurdle from the Naval Research Laboratory believes that once the methane was released from the surface by the impact, it was then ignited by lightning. • As more pockets of methane opened because of the shockwaves, the firestorm spread till it encompassed much of the planet

5. Firestorm (cont.) • Theoretically the gas was burning from the surface high into the atmosphere • The atmosphere itself was burning • The fire would have been hot enough to incinerate land creatures as well as decreasing the oxygen supply and increasing the carbon-dioxide and soot in the atmospere

6. Another Possibility • The impact of such a massive asteroid would launch millions of tons debris into ballistic space flight • Hours after the impact debris would be re-entering Earth’s atmosphere at such high speeds that the radiant heat from the meteors is enough to ignite trees all around the world

7. Long Term Environmental Effects • Such large scale burning of the forests would create large quantities of nitrogen oxides which react with water vapor to form acid rain • If the asteroid impacted rocks with high concentrations of calcium sulfate (found evidence), sulfur dioxide was created which is also a source of acid rain

8. Environmental Changes • The dust from the impact along with soot from the firestorms and smog (effect of fires) would block the sunlight from reaching the planets surface • This would continue for many months, making photosynthesis impossible and causing the normal temperature to drop by over 70 degrees f

9. Environment • After many months, maybe more than a year, the dust and soot would settle and the sun would start heating the land again • Because of the extra carbon dioxide, created from the melting of limestone during the impact and from the fires, the greenhouse effect would start taking over causing Earth’s surface to be at least 10 degrees above normal for a few hundred thousand years

10. Evidence • Erwin Suess and colleagues from the Research Center for Marine Geosciences in Germany, state that there are ‘vast deposits of methane locked in crystals of water ice forming methane hydrates’ under the sea floor. • They also say that these pockets contain more carbon than all the known coal and oil supplies combined

11. Evidence • In the boundary layer, between the Cretaceous period (when dinosaurs roamed) and the Tertiary period (when dinosaurs seem to have disappeared){65 million yrs ago}, there is iridium-bearing clay which is evidence of a large asteroid impact

12. Evidence • The boundary layer also contains soot • The composition and quantity of soot in the layer leads scientists to believe that at least 50% of the world’s forests burned • There are also several signs of large quantities of acid rain at the time including sudden weathering of continental rocks

13. Evidence • 65 Million year old massive crater on the Yucatan peninsula was found by scientists using seismic monitoring equipment to hunt for oil. • There is still debate whether or not this is the actual impact that caused the dinosaur extinction or if it happened 300,000 yrs to early and it was a different impact that caused their demise

14. Conclusion • The impact of a large asteroid could have led to the demise of the dinosaurs in 2 ways • A Global firestorm that incinerated them • Drastic long term environmental changes • So the dinosaurs would have been lucky to be consumed in a firestorm because otherwise they experienced a horrible sequence of events • Large scale fires • Acid rain • No sunlight and drastically cold temperatures • Then extra high temperatures for thousands of years