Laboratory Manual for Introductory Geology

Bradley Deline, Randa Harris, Karen Tefend

Chapter 4 Plate Tectonics - all with Video Answers

Educators

Chapter Questions

There are scientifically important rock deposits in southern Brazil, South America and Angola, Africa that show the northernmost glacial deposits on the ancient continent of Pangaea, which indicates these two areas were once connected. Based on the shape of the two coastlines, give the present day latitude and longitude of two sites along the coast of these countries that used to be connected when the two continents were joined as a part of Pangaea.
Measure in centimeters the distance (Map Length) between the two points you recorded in the previous question. Given that this portion of Pangaea broke apart 200,000, ooo years ago, calculate how fast South America and Africa are separating in $\mathrm{cm} /$ year?

Zachary Warner

Numerade Educator

01:04

Problem 4

When will the next supercontinent form? Examine the Western Coast of South America, the Eastern Coast of Asia, and the Pacific Ocean. If South America and Africa are separating and the Atlantic Ocean is growing, then the opposite must be occurring on the other side of the earth (the Americas are getting closer to Asia and the Pacific Ocean is shrinking). How far apart are North America and Mainland Asia in $\mathrm{cm}$ ? (measure the distance across the Pacific at 40 degrees north latitude- basically measure between Northern California and North Korea)? Take that distance and divide it by the speed you calculated in question 3 to estimate when the next supercontinent will form. Show your work!

Zachary Warner

Numerade Educator

01:00

Problem 5

How far have the snake fossils moved apart since they were originally deposited?
a. 1250 miles
b. 1700 miles
c. 2150 miles
d. 2700 miles

Mishal Gul

Numerade Educator

00:47

Problem 6

Given that this portion of the Australian plate moves at a speed of $2.2$ inches per year, how old are the snake fossils?
a. 310 million years old
b. 217 million years old
c. 98 million years old
d. 62 million years old
e. 34 million years old

Joanna Quigley

Numerade Educator

01:00

Problem 7

There are fossils such as Glossopteris and Lystrosaurus that are found in rocks in South America and Africa that indicate they were part of Pangaea approximately 200 million years ago. These same fossils can be found in Australia, which indicates it, along with Antarctica, was also part of Pangaea at that time. Based on your answer to question 6 which of the following statements about the break-up of Pangaea is TRUE?
a. Australia and Antarctica separated before the break-up of Pangaea.
b. Australia and Antarctica separated during the break-up of Pangaea.
c. Australia and Antarctica separated after the break-up of Pangaea.

Mishal Gul

Numerade Educator

03:01

Problem 8

Consider the ages and positions of the islands listed above along with what you know about plate tectonics and hotspots. In what general direction is the Pacific Plate moving?
a. Northwest
b. Southeast
c. Northeast
d. Southwest

Brenda Sanchez

Numerade Educator

00:51

Problem 9

How fast was the Pacific plate moving during the last $1.1$ million years between the formation of the Big Island and Maui in $\mathrm{cm} /$ year? To calculate this divide the distance (in centimeters) between the two islands by the difference in their ages.

Matthew Biollo

Numerade Educator

00:51

Problem 10

How fast was the Pacific plate moving from $7.2$ million years ago to $4.7$ million years ago between the formation of Kauai and Nihoa in $\mathrm{cm} /$ year? To calculate this divide the distance (in centimeters) between the two islands by the difference in their ages.

Matthew Biollo

Numerade Educator

01:30

Problem 11

Examine the headings of the measurements that you took for the previous two questions. The headings indicate the direction the Pacific Plate is moving over the hot spot. How does the direction of motion of the Pacific Plate during the last $1.1$ million years differ from direction of movement between $4.7$ and 7.2 million years ago? The direction of plate movement in the last $1.1$ million
years ___________.
a. shows no change
b. has become more southerly $\quad$ c. has become more northerly

Jayashree Behera

Numerade Educator

01:11

Problem 12

Zoom out and examine the dozens of sunken volcanoes out past Nihoa, named the Emperor Seamounts. As one of these volcanic islands on the Pacific Plate moves off the hotspot it becomes inactive, or extinct, and the island begins to sink as it and the surrounding tectonic plate cool down. The speed the islands are sinking can be estimated by measuring the difference in elevation between two islands and dividing by the difference in their ages (this method assumes the islands were a similar size when they were active). Calculate how fast the Hawaiian Islands are sinking, by using the ages and elevations of Maui and Nihoa.

Aribah Ali

Numerade Educator

01:59

Problem 13

Using the speed you calculated in the previous question (and ignoring possible changes in sea level), when will the Big Island of Hawaii sink below the surface of the ocean? Divide the current maximum elevation of the Big Island by the rate you calculated in the previous question.

Keshav Singh

Numerade Educator

04:55

Problem 14

Now zoom out to $\sim 4000$ miles eye altitude and look at the chain of Hawaiian Islands again. Notice the chain continues for thousands of miles up to Aleutian Islands (between Alaska and Siberia). Examine the northernmost sunken volcano $(504916.99 \mathrm{~N} 1671636.12 \mathrm{E})$ in this chain. Where was that volcano located when it was still active, erupting, and above the surface of the ocean?
a. $504916.99 \mathrm{~N} 1671636.12 \mathrm{E}$
b $523148.72 \mathrm{~N} 1662543.14 \mathrm{~W}$
c. $274549.27 \mathrm{~N} 1771008.75 \mathrm{~W}$
d. $192815.23 \mathrm{~N} 1551914.43 \mathrm{~W}$

Nidhi Garg

Numerade Educator

01:26

Problem 15

The rock that most closely resembles the composition of continental crust based on the description in the previous section is:
a. $\mathrm{A}$
b. B
c. $\underline{C}$
d. D

Zachary Papazian

Numerade Educator

01:05

Problem 16

Based on the choice you made for question 15 , what is the density of the rocks that make up continental crust? Please give your answer in grams/milliliter.

John Barone

Numerade Educator

02:12

Problem 17

The rock that most closely resembles the composition of oceanic crust based on the description in the previous section is:
a. $A$
b. B
c. $\mathrm{C}$
d. $\mathrm{D}$

Aparna Shakti

Numerade Educator

01:05

Problem 18

Based on the choice you made for question 17 , what is the density of the rocks that make up oceanic crust? Please give your answer in grams/milliliter.

John Barone

Numerade Educator

03:01

Problem 19

Remember, because of isostasy the denser plate will be lower than the less dense plate. If oceanic and continental crust collided, based on their densities the _________ crust would sink below the __________ crust.
a. continental; oceanic
b. oceanic; continental

Brenda Sanchez

Numerade Educator

03:27

Problem 20

According to the geothermal gradient, rocks buried $75 \mathrm{~km}$ beneath the surface would normally be at what temperature?
At $75 \mathrm{~km}$ depth, rocks will be heated to about ________ degrees Celsius.
a. 1500
b. 1250
c. 1000
d. 750

Lisa Tarman

Numerade Educator

01:48

Problem 21

According to the geothermal gradient, rocks at 500 degrees Celsius will be buried how deep?
At 500 degrees Celsius, rocks will be buried to about _________ $\mathrm{km}$ depth.
a. 8
b. $12.5$
c. 20
d. 27

Harsh Gadhiya

Numerade Educator

00:52

Problem 22

What is the physical state of a dry mantle rock at point X?
a. Completely melted
b. Starting to melt
c. Completely solid

Ronald Prasad

Numerade Educator

01:08

Problem 23

What happens when the lithosphere at point $\mathrm{X}$ is heated to $1500{ }^{\circ} \mathrm{C} ?$
a. No change
b. Starts to crystallize
c. Starts to melt

Narayan Hari

Numerade Educator

01:48

Problem 24

At what depth will the dry mantle rock at point $\mathrm{X}$ begin to melt if it is uplifted closer to Earth's surface and its temperature remains the same?
a. $35 \mathrm{~km}$
b. $25 \mathrm{~km}$
c. $18 \mathrm{~km}$
d. $12 \mathrm{~km}$

Harsh Gadhiya

Numerade Educator

01:48

Problem 25

What would happen to the mantle rock at point $\mathrm{X}$ if water is added to it?
a. No change
b. Starts to crystallize
c. Starts to melt

Ivan Kochetkov

Numerade Educator

01:44

Problem 26

Which of the following places represent a Wadati-Benioff zone?
a. $10^{\circ} \mathrm{S}, 110^{\circ} \mathrm{W}$
b. $0^{\circ}, 0^{\circ}$
c. $15^{\circ} \mathrm{S}, 180^{\circ}$
d. $30^{\circ} \mathrm{N}, 75^{\circ} \mathrm{E}$

Ashley High

Numerade Educator

00:30

Problem 27

The Wadati-Benioff zone is associated with which type of plate boundary?
a. Divergent
b. Convergent (Continent-Continent)
c. Convergent (Continent-Ocean or Ocean-Ocean)
d. Transform

Morgan Thompson

Numerade Educator

03:59

Problem 28

Type $344616.16 \mathrm{~N} 1184458.19 \mathrm{~W}$ into the search bar in Google Earth and zoom out to an eye altitude of 10 miles. Quail Lake is a dammed river that is sitting directly over top of the San Andres Fault, which is a well-known transform boundary with the North American Plate on the northern side and the Pacific Plate on the southern side. This boundary is running East-West in this area and you may be able to see the boundary better by zooming out.
Examine the path of the river that feeds into and flows out of Quail Lake. What direction is the North American plate moving in comparison to the Pacific Plate at this location?
a. East
b. West

Jerrah Biggerstaff

Numerade Educator

02:58

Problem 29

Given that San Francisco is located on the North American Plate and Los Angles is located on the Pacific Plate, are these two cities getting closer together or farther apart over time?
a. Closer
b. Farther

Eric Tung

Numerade Educator

03:01

Problem 30

Type " $151948.78 \mathrm{~S} 751203.41 \mathrm{~W}$ " into the Google Earth Search bar. What type of tectonic plates are present?
a. Ocean- Ocean
b. Ocean- Continent
c. Continent- Continent

Brenda Sanchez

Numerade Educator

01:06

Problem 31

What type of plate tectonic boundary is present?
a. Transform
b. Convergent
c. Divergent

Danielle Ashley

Numerade Educator

01:39

Problem 32

Type "6 $2149.68 \mathrm{~S} 293537.87 \mathrm{E}^{\prime \prime}$ into the Google Earth Search bar. What type of process is going on at this location?
a. Seafloor spreading
b. Continental rifting
c. Subduction

William Dunkerton

Numerade Educator

01:39

Problem 33

What features would you expect to occur at this type of boundary?
a. Earthquakes and a trench
b. Volcanoes and a valley
c. Mountains and landslides
d. Earthquakes and offset rivers

William Dunkerton

Numerade Educator

01:00

Problem 34

Type " 2804 27.04N $865526.84 \mathrm{E}$ " into the Google Earth Search bar. What type of tectonic plates are present?
a. Ocean- Ocean
b. Ocean- Continent
c. Continent- Continent

Lauren Levites

Numerade Educator