Mass extinctions

According to paragraph 5, who first suggested the asteroid-impact hypothesis?

• Luis and Walter Alvarez

• A group of geologists from Haiti

• Researchers at the Chicxulub site

• Two scientists from Mexico

According to paragraph 5, what caused the decline in plant life according to the asteroid-impact hypothesis?

• Animals ate too many plants

• The explosion destroyed forests

• The darkened sky reduced photosynthesis

• Water pollution from the asteroid

According to paragraph 5, what does the hypothesis suggest about the speed of the extinction event?

• It happened very slowly

• It lasted for hundreds of years

• It didn’t lead to any real extinction

• It happened very suddenly

According to paragraph 6, why is iridium important to the asteroid-impact hypothesis?

• It is rare on Earth but common in asteroids

• It helps plants grow faster

• It is used to build telescopes

• It is found only in ocean rocks

According to paragraph 6, what does the sudden rise in iridium in sediments suggest?

• Volcanoes released the iridium

• The asteroid impact spread iridium around the world

• Iridium was used in farming

• The Earth’s crust became richer in metals

According to paragraph 6, what is surprising about the evidence found?

• Iridium is easy to find in all places

• Iridium is more common in plants

• Iridium is rare on Earth but found in the sediments

• Iridium is used in farming

According to paragraph 7, what would an asteroid impact create?

• A. A huge crater and signs of heat damage

• B. A change in Earth’s orbit

• C. Large earthquakes and floods

• D. New types of animals

What evidence supports the idea of an impact in the Yucatan Peninsula?

• Discovery of ancient fossils

• Heat-shocked quartz and secondary craters

• Satellite images of plant life

• Reports from ancient civilizations

What is Chicxulub believed to be?

• A. A lost city

• B. A famous volcano

• C. A type of rare mineral

• D. The main crater caused by the asteroid