GeoTours -- Getting Started -- You need to download from both Google Earth TM an

Question

GeoTours -- Getting Started -- You need to download from both Google EarthTM and the kmz file from wwNorton

This can't be done without downloading the program

Go to this address:    http://wwnorton.com/college/geo/essgeo4/geotours.aspx

Click on “download this file” to download GeoTours.kmz which is the file which will run the GeoTours problems on Google.EarthTM By downloading Geotours.kmz you acknowledge that it was created solely to accompany Steve Marshak's Essentials of Geology and is limited to use with only Steve Marshak's Essentials of Geology and may not be reproduced, stored in a retrieval system, or transmitted in any form by any means for any other purpose without the written permission of the publisher.

Follow the instruction to download Google EarthTM

When you double-click on GeoTours.kmz in your file directory you will start Google EarthTM. Then click on Temporary Places, then Geotours.kmz, then Geotours, then Section 2, then Geotour Worksheets.

Then open the Geotour folder you want to explore!

Click on Worksheet B (for Chap. 2): Plate Tectonics,

answer the following 20 questions.

Highlight only the Questions on which you are working (aka uncheck all the others, including the GeoTour Sites). Remember that you can use the transparency slider if you have an overlay.

Continental Drift

1a. Check the box next to “Seafloor Age Map” in the Worksheet 2 folder to view the ages of the oceanic crust around the world. Note that you can use the transparency slider to make this overlay less opaque.

Check and double-click the placemarks for Problem 1 to fly to a location above the Atlantic Ocean. These placemarks represent conjugate points (locations on the opposite sides of an ocean that were once adjacent before seafloor spreading occurred). Although the fit between the African and South American coastlines had been recognized for some time, Wegener carefully matched continental shelves to improve this fit.

Use the Measuring Tool to determine how far these points have moved apart (in km). Zoom in and use the Path tab to create segments along the fracture lineation that offsets the colored ages of the ocean floor.

a)         7190 km

b)         2360 km

c)         5130 km

d)         4320 km

1b. Using the seafloor age map, about how many millions of years ago were these points once adjacent? Beware that the dark blue represents the ocean floor and not the seafloor age. Highlight the Seafloor Age Map layer, and use the transparency slider to make the overlay less transparent so you can determine the correct seafloor age. Use the seafloor age nearest to the points.

a)         110-120 Ma
b)         170-180 Ma
c)         70-80 Ma
d)         40-50 Ma

1c. Using the largest number of the range for your answer to 1b and using the distance for your answer to 1a, calculate the average spreading rate for these points in km/Ma.

a)         36.0 km/Ma
b)         42.75 km/Ma
c)         64.1 km/Ma
d)         4.275 km/Ma

1d. Express your average spreading rate answer for 1c in terms of cm/yr.   (Remember that 1 km = 1000 m = 100000 cm and 1 Ma = 1000000 yrs).

a)         3.6 cm/yr
b)         42.75 cm/yr
c)         6.41 cm/yr
d)         4.275 cm/yr

Divergent Boundaries

2a. Check the box next to “Seafloor Age Map” in the Worksheet 2 folder to view the ages of the oceanic crust around the world. Note: If the plates are moving apart symmetrically at the same rate, then the color band widths are approximately equal.

The placemarks for Problem 2a lie on the crest of a mid-ocean ridge (a divergent boundary) in the Atlantic and Pacific Oceans, respectively. Double-click each placemark and use the color bands representing seafloor ages to determine which divergent boundary is spreading at a faster rate.

a)         Problem 2a-Atlantic
b)         Problem 2a-Pacific
c)         both are spreading at approximately the same rate
d)         one can’t say based on the information provided

2b. Some divergent boundaries spread at different rates. Double-click on the Problem 2b placemark to fly above the East Pacific Rise. Use the color bands representing seafloor ages on either side of this mid-ocean ridge to determine which side is moving faster. Extrapolate using the information in 2a (If the plates are moving apart symmetrically at the same rate, then the color band widths are approximately equal.)

a)         east side
b)         west side
c)         both are spreading at approximately the same rate
d)         one can’t say based on the information provided

2c. In the Layers panel, turn on Borders and Labels and also Gallery > Volcanoes, then double-click on placemark Problem 2c. Divergent boundaries often begin as triple junctions comprised of three “arms” at ~120° apart that may or may not evolve into divergent boundaries. Which of the statements below about this area is INCORRECT?

a)         the NW-trending Red Sea is a linear sea that is opening in a NE-SW direction

b)         the ENE-trending Gulf of Aden is a linear sea that is opening in a NNW-SSE direction

c)         the line of volcanoes define a narrow rift valley that is opening in a NW-SE direction

d)         the line of volcanoes define a volcanic arc related to subduction off the east coast of Africa

Convergent Boundaries

3a. Check the boxes next to “Seafloor Age Map” and “Earthquakes” folders in the Worksheet 2 folder to view the ages of the oceanic crust around the world and selected 1986-2005 earthquakes color-coded by depth, respectively. Also, in the Layers panel, turn on Borders and Labels and Gallery > Volcanoes.

Check and double-click placemark Problem 3a to fly to the Mariana Trench. Which of the following is INCORRECT?

a)         subducting plate is to the east and overriding plate is to the west
b)         subducting plate is to the west and overriding plate is to the east
c)         the line of volcanoes west of the Mariana Trench is the volcanic arc
d)         earthquakes become deeper to the west

3b. Subduction ultimately produces a volcanic arc on the overriding plate (placemark Problem 3b). What depth of earthquakes lies beneath the VOLCANIC ARC associated with the Mariana Trench?

a)         0-50 km
b)         51-100 km
c)         101-200 km
d)         201-400 km

3c. Use the Measuring Tool to determine the arc-trench gap (distance between the volcanic arc and the trench axis, in km) between the placemarks of Problem 3c.

a)         106 km
b)         137 km
c)         212 km
d)         433 km

3d. Check and double-click placemark Problem 3d to fly to the Tonga Trench. What depth of earthquakes lies beneath the VOLCANIC ARC associated with the Tonga Trench?

a)         0-50 km
b)         51-100 km
c)         101-200 km
d)         201-400 km

3e. Use the Measuring Tool to determine the arc-trench gap (in km) between the placemarks of Problem 3e.

a)         245 km
b)         401 km
c)         303 km
d)         190 km

3f. Check and double-click placemark Problem 3f to fly to South America. What depth of earthquakes lies beneath the VOLCANIC ARC associated with this subduction zone?

a)         0-50 km
b)         51-100 km
c)         101-200 km
d)         201-400 km

3g. Which statement best fits your observations of the earthquakes along the subducting slab (Problems 3d and 3f)?

a)        the earthquakes become more shallow further from the trench.

b)         the earthquakes become deeper away from the trench.

3h. Assume that the earthquake depths define the Wadati-Benioff zone for the subducting slab. Compare your answers to Problems 3b, 3d and 3f and choose the statement that best describes your observations.

a)         subducting slabs must reach a depth of 51-100 km before they produce volcanic arcs

b)         subducting slabs must reach a depth of 101-200 km before they produce volcanic arcs

c)         subducting slabs must reach a depth of 201-400 km before they produce volcanic arcs

d)         volcanic arcs don’t seem to have a systematic relationship with the subducting slab

Transform Faults

4a. Not available.

4b. Check the boxes next to “Seafloor Age Map” in the Worksheet 2 folder to view the ages of the oceanic crust around the world. Also, in the Layers panel, turn on Borders and Labels as well as Gallery > Earthquakes.

            Check and double-click the placemarks for Problems 4b-I and 4b-ii to the Mid-Atlantic Ridge. These placemarks point to a segment of an active transform fault. Which direction are the placemarks for Problem 4b-i and 4b-ii moving, respectively?

a)         east, west
b)         west, east
c)         both east
d)         both west

4c. Which direction are the placemarks for Problem 4c-i and 4c-ii moving, respectively?

a)         east, west
b)         west, east
c)         both east
d)         both west

4d. Check and double-click the placemark for Problem 4d. Given the offset shown here, what type of transform fault is the San Andreas Fault?

a)         right-lateral
b)         left-lateral

Hot Spots

5a. Check the boxes next to “Seafloor Age Map” in the Worksheet 2 folder to view the ages of the oceanic crust around the world. Also, in the Layers panel, turn on Borders and Labels as well as Gallery > Volcanoes.

Check and double-click the folder Problem 5 to fly to the Pacific Ocean where you will have a view of the Hawaiian Island-Emperor Seamount hotspot chain with their age of formation (Ma). Use the Measuring Tool to measure the distance between Midway Atoll and Kilauea and calculate the average velocity of the Pacific Plate in cm/yr. Use what you learned in questions 1a-1d.

a)         1.9 cm/yr
b)         4.1 cm/yr
c)         8.8 cm/yr
d)         15 cm/yr

5b. What is the approximate age of the BEND (as designated by the 5b pin) in the Hawaiian Island-Emperor Seamount chain?

a)         120 Ma
b)         150 Ma
c)         32 Ma
d)         43 Ma

Explanation / Answer

1a. Check the box next to “Seafloor Age Map” in the Worksheet 2 folder to view the ages of the oceanic crust around the world. Note that you can use the transparency slider to make this overlay less opaque.

Check and double-click the placemarks for Problem 1 to fly to a location above the Atlantic Ocean. These placemarks represent conjugate points (locations on the opposite sides of an ocean that were once adjacent before seafloor spreading occurred). Although the fit between the African and South American coastlines had been recognized for some time, Wegener carefully matched continental shelves to improve this fit.

Use the Measuring Tool to determine how far these points have moved apart (in km). Zoom in and use the Path tab to create segments along the fracture lineation that offsets the colored ages of the ocean floor.

a)         7190 km

b)         2360 km

c)         5130 km                                   Answer : C 5130 km

d)         4320 km

1b. Using the seafloor age map, about how many millions of years ago were these points once adjacent? Beware that the dark blue represents the ocean floor and not the seafloor age. Highlight the Seafloor Age Map layer, and use the transparency slider to make the overlay less transparent so you can determine the correct seafloor age. Use the seafloor age nearest to the points.

a)         110-120 Ma
b)         170-180 Ma                 Answer: 170-180 Ma
c)         70-80 Ma
d)         40-50 Ma

1c. Using the largest number of the range for your answer to 1b and using the distance for your answer to 1a, calculate the average spreading rate for these points in km/Ma.

a)         36.0 km/Ma                              Answer = 36.0 km/Ma
b)         42.75 km/Ma
c)         64.1 km/Ma
d)         4.275 km/Ma

1d. Express your average spreading rate answer for 1c in terms of cm/yr.   (Remember that 1 km = 1000 m = 100000 cm and 1 Ma = 1000000 yrs).

a)         3.6 cm/yr                                  Answer: 3.6 cm/year
b)         42.75 cm/yr
c)         6.41 cm/yr
d)         4.275 cm/yr

Divergent Boundaries

2a. Check the box next to “Seafloor Age Map” in the Worksheet 2 folder to view the ages of the oceanic crust around the world. Note: If the plates are moving apart symmetrically at the same rate, then the color band widths are approximately equal.

The placemarks for Problem 2a lie on the crest of a mid-ocean ridge (a divergent boundary) in the Atlantic and Pacific Oceans, respectively. Double-click each placemark and use the color bands representing seafloor ages to determine which divergent boundary is spreading at a faster rate.

a)         Problem 2a-Atlantic
b)         Problem 2a-Pacific       Answer: Pacific floor spreading at faster rate
c)         both are spreading at approximately the same rate
d)         one can’t say based on the information provided

2b. Some divergent boundaries spread at different rates. Double-click on the Problem 2b placemark to fly above the East Pacific Rise. Use the color bands representing seafloor ages on either side of this mid-ocean ridge to determine which side is moving faster. Extrapolate using the information in 2a (If the plates are moving apart symmetrically at the same rate, then the color band widths are approximately equal.)

a)         east side                  Answer : east side
b)         west side
c)         both are spreading at approximately the same rate
d)         one can’t say based on the information provided

2c. In the Layers panel, turn on Borders and Labels and also Gallery > Volcanoes, then double-click on placemark Problem 2c. Divergent boundaries often begin as triple junctions comprised of three “arms” at ~120° apart that may or may not evolve into divergent boundaries. Which of the statements below about this area is INCORRECT?

a)         the NW-trending Red Sea is a linear sea that is opening in a NE-SW direction

b)         the ENE-trending Gulf of Aden is a linear sea that is opening in a NNW-SSE direction                   Answer: incorrect

c)         the line of volcanoes define a narrow rift valley that is opening in a NW-SE direction

d)         the line of volcanoes define a volcanic arc related to subduction off the east coast of Africa

Convergent Boundaries

3a. Check the boxes next to “Seafloor Age Map” and “Earthquakes” folders in the Worksheet 2 folder to view the ages of the oceanic crust around the world and selected 1986-2005 earthquakes color-coded by depth, respectively. Also, in the Layers panel, turn on Borders and Labels and Gallery > Volcanoes.

Check and double-click placemark Problem 3a to fly to the Mariana Trench. Which of the following is INCORRECT?

a)         subducting plate is to the east and overriding plate is to the west
b)         subducting plate is to the west and overriding plate is to the east   Answer: Incorrect
c)         the line of volcanoes west of the Mariana Trench is the volcanic arc
d)         earthquakes become deeper to the west

3b. Subduction ultimately produces a volcanic arc on the overriding plate (placemark Problem 3b). What depth of earthquakes lies beneath the VOLCANIC ARC associated with the Mariana Trench?

a)         0-50 km
b)         51-100 km
c)         101-200 km                            Answer: 101-200 km
d)         201-400 km

3c. Use the Measuring Tool to determine the arc-trench gap (distance between the volcanic arc and the trench axis, in km) between the placemarks of Problem 3c.

a)         106 km
b)         137 km
c)         212 km                         Answer: 212 km
d)         433 km

3d. Check and double-click placemark Problem 3d to fly to the Tonga Trench. What depth of earthquakes lies beneath the VOLCANIC ARC associated with the Tonga Trench?

a)         0-50 km
b)         51-100 km
c)         101-200 km                             Answer: 101 - 200 km
d)         201-400 km

3e. Use the Measuring Tool to determine the arc-trench gap (in km) between the placemarks of Problem 3e.

a)         245 km
b)         401 km
c)         303 km
d)         190 km                                    Answer: 190 km

3f. Check and double-click placemark Problem 3f to fly to South America. What depth of earthquakes lies beneath the VOLCANIC ARC associated with this subduction zone?

a)         0-50 km
b)         51-100 km
c)         101-200 km                 Answer; 101-200 km
d)         201-400 km

3g. Which statement best fits your observations of the earthquakes along the subducting slab (Problems 3d and 3f)?

a)        the earthquakes become more shallow further from the trench. Answer: a)

b)         the earthquakes become deeper away from the trench.

3h. Assume that the earthquake depths define the Wadati-Benioff zone for the subducting slab. Compare your answers to Problems 3b, 3d and 3f and choose the statement that best describes your observations.

a)         subducting slabs must reach a depth of 51-100 km before they produce volcanic arcs

b)         subducting slabs must reach a depth of 101-200 km before they produce volcanic arcs                                Answer: b)

c)         subducting slabs must reach a depth of 201-400 km before they produce volcanic arcs

d)         volcanic arcs don’t seem to have a systematic relationship with the subducting slab

Transform Faults

4a. Not available.

4b. Check the boxes next to “Seafloor Age Map” in the Worksheet 2 folder to view the ages of the oceanic crust around the world. Also, in the Layers panel, turn on Borders and Labels as well as Gallery > Earthquakes.

            Check and double-click the placemarks for Problems 4b-I and 4b-ii to the Mid-Atlantic Ridge. These placemarks point to a segment of an active transform fault. Which direction are the placemarks for Problem 4b-i and 4b-ii moving, respectively?

a)         east, west
b)         west, east
c)         both east                      Answer: both east
d)         both west

4c. Which direction are the placemarks for Problem 4c-i and 4c-ii moving, respectively?

a)         east, west
b)         west, east
c)         both east                      Answer: both east
d)         both west

Related Questions

Navigate

• Browse (All)
• Browse G
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.