Cretaceous Ground Zero
Read the article "Cretaceous Ground Zero" from the June 1991 issue of Natural History and answer these questions in complete sentences:
- Why did Berkeley scientists first measure the iridium in the pencil-thick sheet of gray clay found in Gubbio Italy ?
- How many times the expected level of iridium did they find?
- Where did they decide the extra iridium came from?
- What were two other pieces of evidence found to support the meteorite impact theory?
- What is the "ejecta layer"?
- Describe the ejecta layer in Haiti?
- Why was the thickness of the ejecta layer in Haiti important?
- What did scientists use to determine that the meteor had struck on the edge of an ocean basin?
- How did the K-T boundary deposits in Cuba support the ocean impact hypothesis?
- How did ocean-bottom sediment disturbance help narrow the search for the impact site?
- What did the researchers look for when they found a circular geologic feature?
- The meteor impact would have produced immediate lethal effects, but what other effect would have made the Chicxulub impact even more destructive?
- Which crater is the impact crater?