Exam 14: Impacts and Extinctions

A) During the Earth's history there have been only a few meteorite impacts due to the protection by the Earth's atmosphere, which vaporizes nearly all meteorites.
B) When a large meteorite strikes the Earth, there is a shock wave that compresses, heats, melts, and excavates earth materials.
C) Meteorite impact craters cannot be distinguished from volcanic craters.
D) Meteor Crater in Arizona has been accepted as having formed by a meteorite impact since it was discovered by geologists in the late nineteenth century.
E) Impact craters are all roughly the same size.

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A) Blow it up in space before it enters our atmosphere
B) Divert it so that it doesn't collide with Earth
C) Allow our atmosphere to vaporize it
D) Send the space shuttle up to tow it out into space
E) Evacuate areas that would be impacted

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False

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Impacts involve extremely high velocity, energy, pressure, and temperatures. Most of the energy of the impact is in the form of kinetic energy. This energy is transferred to Earth's surface through a shock wave that propagates into Earth. The shock wave compresses, heats, melts, and excavates earth materials. It is this transfer of kinetic energy that produces the crater. The shock can metamorphose some rocks in the impact area, while others are melted and mixed with the materials of the impacting object itself. Most of the metamorphism consists of high-pressure modifications of minerals, such as quartz. These modifications are characteristic of meteorite impact, so they are extremely helpful in confirming the origin of an impact crater.

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The K-Pg extinction brought an end to the large dinosaurs, which had been at the top of the food chain for 100 million years or more. Their demise allowed small mammals to diversify and evolve into the approximately 4000 species, including humans, that are alive today.

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A) About one thousand to ten thousand years
B) About 100 thousand to one million years
C) About ten million to 100 million years
D) About 1 billion to 10 billion years

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Most hypotheses for mass extinctions inv...

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A) They found evidence of a giant tsunami on the Gulf coast.
B) They found evidence of an impact crater in Mexico.
C) They found evidence of wildfires in many regions throughout the globe.
D) They found evidence of Iridium enrichments in a clay layer that led them to believe that the Iridium was the remains of a meteorite impact.
E) They found evidence of acid rain in the rocks in the Southern Hemisphere.

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A) Asteroid
B) Meteoroid
C) Meteor
D) Comet
E) Cupid

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A) It was in a remote part of the world where nobody lives.
B) It was too small for anyone to notice.
C) It was destroyed by plate tectonic processes.
D) It was buried by sedimentary rock and the seafloor.
E) It was buried in snow and ice.

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A) The incidence of large asteroid impacts is rare.
B) Risk, although relatively high, is averaged over thousands of years.
C) Scientists are working on methods to prevent possible asteroid impacts.
D) The Earth's atmosphere will vaporize all asteroids before they reach the ground.

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A) Large diameter (10m-1000km) object originating from belt between Jupiter and Mars
B) Moderate diameter (<10m) object originating from collisions of asteroids
C) Small diameter (<10 cm) object destroyed in Earth's atmosphere
D) Variable-sized object that intersects the Earth's surface
E) Icy object that appears to have a tail as it burns, originates from outside our solar system

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