Study Guide Chapter 14
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Exam 4 Study Guide: Part 4
Chapter 14: Impacts and Extinctions
1.
Describe how the solar system formed. Include ages.
The solar system formed approximately 4.6 billion years ago from a rotating, collapsing gas
and dust cloud called the solar nebula. The Sun formed at the center, and the leftover
material in the disk around it coalesced to form planets, moons, asteroids, and comets.
2.
Describe the differences between an asteroid, meteor, comet, meteoroid, and
meteorite.
Asteroids, meteoroids, and meteorites are rocky or metallic fragments in space, with
meteoroids being smaller than asteroids. Meteors are the streaks of light produced when
meteoroids enter Earth's atmosphere, and meteorites are the fragments that reach the
Earth's surface. Comets, on the other hand, are composed of ice, dust, and volatile
compounds and develop bright tails when they approach the Sun.
3.
Define airburst. List the two airburst that occurred in Russia.
An airburst is an explosion that occurs in the atmosphere rather than upon impact with the
Earth's surface. Notable airbursts include the Tunguska event in 1908 and the Chelyabinsk
event in 2013, both of which happened in Russia.
4.
Why does the Earth have so few impact craters compared to the Moon?
Earth has fewer impact craters than the Moon because its dynamic processes, such as
erosion, plate tectonics, and weathering, continually modify the surface, gradually removing
or altering evidence of past impacts. The Moon lacks these processes, preserving impact
craters for longer periods.
5.
Differentiate between simple and complex craters.
Simple craters have a bowl-shaped structure and are typically smaller, while complex craters
are larger and exhibit a central peak or ring structures due to the rebound of the crater floor
after impact.
6.
Define catastrophism, uniformitarianism (gradualism), and punctuated
uniformitarianism.
Catastrophism posits that sudden, short-lived, and violent events shape Earth's geology.
Uniformitarianism (gradualism) argues that geological processes occur slowly and steadily
over time. Punctuated uniformitarianism combines aspects of both, acknowledging that while
most processes are gradual, some are punctuated by sudden events.
7.
Define mass extinction. What are the hypotheses for the cause of mass extinctions?
A mass extinction involves a significant, global decrease in biodiversity. Hypotheses for their
causes include asteroid impacts, volcanic activity, climate change, and combinations of these
factors.
8.
What caused the K-Pg mass extinction, and what is the main evidence to support the
event?
The K-Pg mass extinction, which occurred approximately 66 million years ago, was likely
caused by a large asteroid impact. The main evidence includes a layer of iridium-rich
sediment found globally, known as the Cretaceous-Paleogene (K-Pg) boundary, along with
impact crater structures such as the Chicxulub crater in Mexico.
9.
How can we minimize the impact hazard?
Minimizing the impact hazard involves tracking near-Earth objects, developing technologies
for deflection, and enhancing international collaboration on planetary defense efforts.
10.
Explain the various hazards linked to a large extraterrestrial impact.
Hazards linked to a large extraterrestrial impact include direct effects like shock waves,
thermal radiation, and crater formation. Indirect effects encompass tsunamis, wildfires,
climate disruption, and long-term ecological changes, posing significant threats to human
civilization and ecosystems.
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