Geology 110: Earth and Space Science - Spaces Login



Geology 110: Earth and Space Science

Chapter 8 (Geologic Time) Homework

SELF-REFLECTION AND COMPREHENSION SURVEYS

Checkpoint 8.1, p. 212

#1: Place the following events that were described in the earlier chapters of the book in the correct relative chronological order, from earliest to the most recent.

a. Tsunami struck Japan.

b. Ice sheet was present in India.

c. Asteroid collided with Yucatan Peninsula.

d. Mount Pinatubo erupted in the Philippines.

e. Wegener developed the continental drift hypothesis

Correct order is:

Checkpoint 8.2, p. 216

#2: Examine the following image of rock layers and answer Questions 1 and 2 about relative time.

I. Which statement is most accurate?

a. D is older than B

b. E is older than A

c. F is older than C

II. When did the tilting of the layers occur?

a. After A was deposited b. Between deposition of layers E and A

c. Before B was deposited d. Between deposition of layers C and E

[pic]

Checkpoint 8.3, p. 217

#3: Use the principles of original horizontality, superposition, cross-cutting relationships, and inclusions to determine the order of events for the idealized location shown in the following diagram.

a) Place the rock units in their order of formation, oldest to youngest.

[pic]

Checkpoint 8.5, p. 220

#4: Geologists look for similar rock types or fossils to tell them that geologic environments were similar between two widely spaced locations. Can we do the same kind of thing? What are some examples of modern environments that have characteristic types of plants and animals?

Checkpoint 8.6, p. 220

#5: Outcrops of rock are examined in four different locations in a state. The rock types and the fossils they contain are illustrated in the following diagram.

a. Which fossil would be the best choice to use as an index fossil for these rocks?

a) Fossil 1 b) Fossil 2 c) Fossil 3

b. Which fossil is least characteristic of a specific set of geological conditions?

a) Fossil 1 b) Fossil 2 c) Fossil 3

[pic]

Checkpoint 8.7, p. 221

#6: Examine the following illustration and predict which rock unit in the Grand Canyon is most likely to have formed in a depositional environment like the one pictured.

[pic]

Checkpoint 8.11, p. 226: Ancient Leaves and Insect Extinctions

#7. Read the following abbreviated version of a newspaper article (above) and answer these questions. Please designate sections of your answer as A., B. and C., so I know which question you are answering:

 

a. What was the question being investigated by the scientists?

 

b. What observations did the scientists make during their investigations?

 

c. What was the principal conclusion of their research?

When a 6-mile-wide asteroid slammed the Earth 65 million years ago, it wiped out the dinosaurs, about 80 percent of the world’s plant species, and all animals bigger than a cat. But what happened to the bugs?

 

It’s been tough for scientists to determine how the insects fared because they rarely leave behind fossils, but a Denver paleontologist and his Smithsonian Institution colleagues found a way around the problem. By studying insect damage etched into thousands of fossil leaves, they determined that many plant-eating bugs perished in the big impact.

 

“These little insects are leaving their calling cards on the fossil leaves, and we have an excellent fossil record of leaves,” said Kirk Johnson, curator of paleontology at the Denver Museum of Nature & Science. “So by looking at the insect damage on the leaves before and after the dinosaur extinctions, we can make a pretty good educated guess of what happened to the insects.”

 

Johnson and his collaborators estimate that 55% to 60% of plant-eating insects were exterminated. Over the past 20 years, Johnson has collected 13,441 plant fossils from quarries in southwestern North Dakota. When the asteroid hit Mexico’s Yucatan Peninsula, it threw up clouds of dust that traveled around the globe. Johnson pulled the fossils from rock layers directly above and below those sediments. At the time, southwestern North Dakota was a warm, forested plain with lots of broad-leafed trees.

 

Some leaves, now stored at the Denver museum and at Yale University, are up to a foot long. Individual leaf veins are visible, as are the diagnostic chomp marks, tunnels, and holes left by prehistoric beetles, grasshoppers, butterflies, and moths. Some insects are specialists, rely on a single species of plant for sustenance; others are generalists that feed on several plant types. By analyzing insect-damaged leaves before and after the impact, the researchers determined that the generalists survived, while 70% of the specialists did not.

Source: Rocky Mountain News (Denver, CO), February 22, 2002, Page 7A: Jim Erickson.

 

Checkpoint 8.14, 231

A) The isotope of element X has 15 protons, 17 neutrons and 15 electrons. The element has an atomic number of _________ and a mass number of ________.

B) If radioactive decay began with 400,000 parent isotopes, how many would be left after three half lives?

i) 200,000

ii) 100,000

iii) 50,000

iv) 25,000

Checkpoint 8.18, p. 234: Rates Timeline

#8: Events happen on Earth over periods of time that vary from seconds to millions of years. Place each of the following events in the appropriate location on the timeline provided here, according to either its frequency (how often?) or the length of time over which it occurs (how long?).

1. The time between large eruptions of the same volcano

2. A season (e.g., spring)

3. Time between great earthquakes on the San Andreas Fault

4. Period required to form the Atlantic Ocean

5. Formation and decay of a tornado

6. Earth’s orbit around the sun

7. Length of orbit for a long-period comet

8. Time between mass extinctions

9. Time required to carve the Grand Canyon

10. Growth of major U.S. cities

11. Formation and decay of a hurricane

YOU CAN USE THE CHART BELOW TO ANSWER THE QUESTION ABOVE:

|TIME |NUMBERED ANSWER(S) |

|ONE SECOND | |

|to | |

|ONE MINUTE | |

|to | |

|ONE DAY | |

|to | |

|ONE YEAR | |

|to | |

|ONE HUNDRED YEARS | |

|to | |

|ONE THOUSAND YEARS | |

|to | |

|ONE MILLION YEARS | |

|to | |

|ONE HUNDRED MILLION YEARS | |

|to | |

|ONE THOUSAND MILLION YEARS (OR ONE BILLION YEARS) | |

Checkpoint 8.16, p. 232 (Optional extra credit)

#9: The following diagram represents three rock exposures containing fossils. Each exposure contains a layer of volcanic ash (in red) that has been dated by the analysis of 238U/206Pb isotopes.

[pic]

a) Place the fossils in the correct order according to their relative ages, from oldest to youngest:

b) Explain how you would estimate the potential age ranges of the C, G, and K fossils based on the ages determined for the three volcanic ash layers.

(Question adapted from J. Dodick and N. Orion, “Measuring student understanding of geological time,” Science Education, 2003, vol. 87, pp. 708-731.)

-----------------------

Youngest

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Oldest

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download