Exam 15: Meteorite Impacts and Extinctions

Describe the logic behind using iridium concentrations to determine rates of sedimentation.Under what conditions do the assumptions in this method break down? How is iridium concentration linked to the mass extinction at the K-T boundary?

Shoemaker-Levy 9 was an unusual comet in that it

What is an ejecta blanket?

What are three other natural hazards that might be linked to an impact event?

The Sudbury Impact Basin is famous for nickel-copper-platinum deposits.How is this related to the impact event?

Scientific acceptance of the idea that asteroids could strike Earth and wreak havoc is relatively recent.What event made this possibility become nearly universally accepted?

The Tunguska event in Siberia in 1908 produced a crater about 1 km in diameter.

What triggered the formation of the sun?

According to astronomical evidence,approximately how long ago did the Big Bang occur?

At present,what is the smallest sized asteroid that we are able to detect and track?

Iridium is a platinum group metal

The tail of a comet is produced when icy material melts and gas and dust are shed from the comet.

What is the significance of the rock Breccia in an impact crater?

Why are impact craters we observe today on Earth not as deep as the initial impact crater?

Why are there no craters older than 350 million years old found on any of the oceanic plates?

All extinction events occur due to a geologic or impact event.

About once per month,an object about 10 metres in diameter explodes in Earth's upper atmosphere.

If scientists spot an object that might collide with Earth,they will probably have thousands of years to study it before the collision.

In your opinion,why should humans be concerned with the causations of past extinction events?

What is a meteor?