Impacts & Extinctions

Question 1

Where are asteroids found?

Answer 1

In the asteroid belt between Mars and Jupiter

Question 2

Define meteoroids

Answer 2

Broken up asteroids

Question 3

Define meteors

Answer 3

Meteoroids that enter Earth’s atmosphere (shooting stars)

Question 4

Define meteorites

Answer 4

Meteors that hit Earth’s surface

Question 5

What is the speed that objects enter Earth’s atmosphere?

Answer 5

7 to 45 miles per second

Question 6

What is an airburst?

Answer 6

A meteoroid that explodes in the atmosphere

Question 7

What was interesting about the Chelyabinsk airburst in 2013?

Answer 7

It was the largest known asteroid to enter Earth’s atmosphere since Tunguska airburst in 1908

Question 8

Why was the Chelyabinsk asteroid not observed before it struck the Earth?

Answer 8

Meteor astrophysicists were tracking a different asteroid

Question 9

What was the most powerful natural explosion in recent Earth history?

Answer 9

The Tunguska asteroid, releasing energy equivalent to ~185 Hiroshima bombs

Question 10

What are the craters on the Moon so well preserved?

Answer 10

The moon has no geological activity or erosion so craters are not erased.

Question 11

Define mass extinction

Answer 11

Sudden loss of large numbers of plants and animals relative to number of new species being added

Question 12

What are three possible triggers for a mass extinction?

Answer 12

1-plate tectonics
2-volcanic activity
3-meteorite impact or airburst

Question 13

How many major mass extinctions have occurred?

Answer 13

Six

Question 14

During the Great Permian Extinction, ___% of all vertebrate species on land and ___% of marine organisms were destroyed.

Answer 14

70% and 90%

Question 15

What is the possible cause of the Great Permian Extinction?

Answer 15

Large basaltic volcanic eruptions in Siberia

Question 16

What animal thrived after the Permian Extinction?

Answer 16

Reptiles

Question 17

What is the Mesozoic often called?

Answer 17

“Age of Reptiles”

Question 18

For how many years did dinosaurs rule the land?

Answer 18

180 million years

Question 19

How long have the modern form of humans been around?

Answer 19

200,000 years

Question 20

Besides dinosaurs, what other organism ruled during the Cretaceous Period?

Answer 20

Giant crocodiles

Question 21

It is estimated that ___ of all plant and animal species went extinct at the end of the Mesozoic.

Answer 21

3/4

Question 22

What is thought to have caused this extinction?

Answer 22

A large meteorite strike at the Yucatan Peninsula 65 million years ago

Question 23

What evidence is there for an asteroid collision 65 million years ago?

Answer 23

1-cm thick layer of sediment containing high level of iridium

Question 24

What is the shorthand for the Cretaceous-Paleogene boundary?

Answer 24

K-Pg (used to be termed the K-T boundary)

Question 25

How big was the crater in the Yucatan peninsula?

Answer 25

125 miles in diameter and 25 miles deep

Question 26

What were some of the devastating effects of this impact?

Answer 26

-dust and debris blocks sunlight -sulfuric acid enters atmosphere -fireball sets off wildfires around the globe -tsunamis reach over 1000 ft high

Question 27

What is happening on Earth one month after the impact?

Answer 27

-there is no sunlight and no photosynthesis -acid rain -food chain has stopped

Question 28

What is happening on Earth several months after the impact?

Answer 28

-sunlight returns -acid rain stops -ferns restore burned landscape

Question 29

How often do impacts of this size occur?

Answer 29

Once every 40 to 100 million years

Question 30

In the Cenozoic ___________ replace the reptiles as dominant vertebrate life forms on land.

Answer 30

mammals

Question 31

In the Cenozoic mammal groups became very large. What are some examples of these large mammals?

Answer 31

-wooly mammoths -giant ground sloths -saber toothed tigers

Question 32

What is special about the La Brea Tar Pits in Los Angeles?

Answer 32

The tar pits trapped over 650 species of Ice Age animals such as the mammoth, plus one human skeleton

Question 33

When did the Pleistocene epoch end?

Answer 33

11,000 years ago

Question 34

What was the climate like in the Pleistocene?

Answer 34

Warmer as evidenced by the ice sheets and glaciers receding

Question 35

What recent theory explains the disappearance of large Pleistocene mammals and the Clovis people 12,900 years ago?

Answer 35

An airburst caused intense wind and wildfires that destroyed forests and grasslands. The atmosphere was polluted with soot and toxic fumes.

Question 36

What are ways to minimize hazards from an asteroid impact?

Answer 36

-blow it up in space -nudge it out of Earth's orbit -evacuation of impact point

Question 37

What are some other theories on what wiped out the large mammals of the Pleistocene?

Answer 37

They were hunted to extinction, or climate warming at the end of the Ice Age weakened them.

Question 38

What epoch began at the end of the Ice Age and continues to present day?

Answer 38

The Holocene epoch