Re: do mass extinctions have anything to do with asteroid impacts?

Date: Tue Jan 26 11:25:17 1999
Posted By: Kevin Tuttle, Undergrad student, Biology, Georgia Institute of Technology
Area of science: Astronomy
ID: 916079092.As

Message:

Several times in earth's history, there have been mass extinctions. in school we are trying to figure out if there is a correlation between asteroid impacts and mass extinctions. is there any evidence that mass extinctions are caused by asteroid impacts?

Actually, meteorite impact is currently the most popular theory to explain the mass extinction at the end of the Cretaceous Period. Every year there is more evidence in support of this theory. It was most strengthened by Luis and Walter Alvarez. They discovered the element iridium between the Cretaceous and the Tertiary layers of the Earth. This element is very rare on Earth, however it is quite abundant in meteorites.

Later, a crater was found along the Mexican Yucatan Peninsula. It is believed that this is where that asteroid struck as its depth and iridium content coincide with what would be expected had a meteroite stuck the Earth at that time.

Like so many other things in science, though, this is only a theory. There are many other theories that have been suggested that are quite possible, though few as compelling. Other theories sometimes add to the meteorite-impact theory. For example, some claim that the species that became extinct (anything weiging over 25kg, including the dinosaurs) were on the decline anyway and the meteorite-impact just sped up the process.

There's more information on this particular mass-extinction at: The KRSS[Earth Science 11] Dinosaur Extinction Project

If you have any further questions, please feel free to E-mail me.

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