Laboratory 2 : Plate Tectonics and the Rock Cycle: ESS 101 B Au 21: Introduction To Geology And Societal Impacts
Laboratory 2 : Plate Tectonics and the Rock Cycle
Due Oct 24 at 11:30pm Points 16 Questions 41
Available Oct 8 at 9am - Oct 24 at 11:30pm 17 days Time Limit None Allowed Attempts 3
Instructions
Use the quiz questions below to complete the answer sheet for the Laboratory 2 (Plate Tectonics and the Rock Cycle)
exercise. This lab is worth a total of 15 points.
The Prelab Video serves as an introduction to the topics covered in this lab. Find the Prelab Video here
(https://www.youtube.com/watch?v=b5P_OQ_5gyg&feature=youtu.be) .
NOTE ABOUT IMAGES : You can find all of the figures embedded in this quiz in Files --> Lab Instructions--> Lab 2: Plate Tectonics & the Rock
Cycle. Figures in the Questions are in that folder and are labeled with the relevant question number. Figures in the Introduction are within the folder
Figures in Introduction.
Lab 2 PDF file.
You have two attempts for this quiz.
This quiz was locked Oct 24 at 11:30pm.
Attempt History
Attempt Time Score
KEPT Attempt 2 13 minutes 14 out of 16 *
LATEST Attempt 2 13 minutes 14 out of 16 *
Attempt 1 53 minutes 13.75 out of 16 *
* Some questions not yet graded
Score for this attempt: 14 out of 16 *
Submitted Oct 20 at 11:42am
This attempt took 13 minutes.
Question 1 0..25 pts
Laboratory Honor Statement
Cheating or plagiarism of any kind will not be tolerated in ESS 101. This includes copying
answers from a friend or classmate, copying answers verbatim found on the internet or
other literary sources, or copying any work that may answer the question being asked.
Make sure you always use your own words when answering the questions in the homework
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, Laboratory 2 : Plate Tectonics and the Rock Cycle: ESS 101 B Au 21: Introduction To Geology And Societal Impacts
and cite appropriate references if you use them to help you answer the question. Anyone
caught violating the academic code of conduct (https://www.washington.edu/cssc/for-
students/academic-misconduct/) will receive a “0” grade on the assignment, and if the
conduct is deemed egregious, reported to the UW Academic Misconduct representative.
I acknowledge that I have carefully read and understand the above statement regarding the
consequences of cheating and plagiarism, and promise to complete my work in this class
with honesty and integrity. Answer "True" below supporting your acknowledgement.
True
False
Learning Goals:
By completing this lab, students will become more familiar with:
The three types of plate boundaries: convergent, divergent, and transform
The different types of magma associated with each type of plate boundary
The plate tectonic map of the Circum-Pacific Basin
The relationship between plate tectonics, volcanoes, and earthquakes
The Hawaii-Emperor Seamount chain and using distance-time relationships of the
volcanic islands to describe historical tectonic movement
Plate Tectonics
Overview
Plate tectonics links together many aspects of geology. Plate tectonics describes how the
earth’s thin, outer lithosphere is broken into plates that slowly move over the
asthenosphere (Figure 2-1). These brittle rock plates have thicknesses of 10 to 100 km and
move over the ductile rock of the asthenosphere at rates of 1 to 10 cm/year. This is about
the same rate at which your fingernails grow! The forces that drive plate motion are
primarily ridge-push and slab-pull gravity forces. See Incorporated Research Institutions for
Seismology video on the forces that drive plate tectonics (select animation tab).
(https://www.iris.edu/hq/inclass/animation/what_are_the_forces_that_drive_plate_tectonics)
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Figure 2-1: Earth’s tectonic plates. The black lines indicate the boundaries between plates, and the
red arrows indicate the relative motions at plate boundaries1.
Chemical and physical layers of the earth
Earth’s structure can be classified by chemical composition or by physical properties. The
chemical layers of the Earth are the crust, mantle, and core. The crust is mainly composed
of igneous rocks (that is, rocks that formed when hot magma cooled at earth’s surface).
Continental crust is made of felsic (silica-rich) rocks like granite, and oceanic crust is
made of mafic (silica-poor) rocks such as basalt. Below the crust is the mantle, which is
made of silicate minerals that are rich in iron and magnesium. Generally, rocks that are
silica-rich tend to have relatively lower iron-magnesium (Fe-Mg) content.
The physical layers of the outer earth are the lithosphere and the asthenosphere (Figure 2-
2). Tectonic plates are pieces of the lithosphere, a layer of brittle rock. The plates slide
over the asthenosphere, a layer of ductile, mantle rock.
Figure 2-2: Cross-section of the outer solid Earth2. The lithospheric plates slide over the
asthenosphere. Oceanic lithosphere forms at mid-ocean ridges (divergent margins) and descends
back into the asthenosphere in subduction zones (convergent margins).
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Plate Boundaries
Volcanoes and mountains form at plate boundaries, and plate boundaries produce strong
earthquakes. There are three types of plate boundary:
1. Divergent, where two plates are moving apart.
2. Convergent, where two plates are moving together. There are three different types of
convergent margins:
Ocean-ocean, where oceanic crust converges with oceanic crust. At this type of
margin, the denser of the two plates will dive beneath the other, and create a
subduction zone (e.g. the Marianas Trench).
Ocean-continent, where oceanic crust converges with continental crust. At this
type of margin, the denser oceanic crust will dive beneath the less dense continental
crust and create a subduction zone (e.g. the Cascadia subduction zone).
Continent-continent, where continental crust converges with continental crust. At
this type of margin, both plates are relatively buoyant and do not want to sink down.
Therefore, subduction does not occur and the two plates collide together to form
mountain ranges such as the Himalaya Mountains (formed by the collision of the
Indian and Eurasian plates).
3. Transform, where two plates with ocean and/or continental crust are sliding past each
other.
Volcanoes
Volcanoes are places where liquid rock erupts onto the surface of the earth. Volcanoes
often form at divergent and convergent boundaries, but they can also form in the middle of
plates due to mantle hot spots or rifting. Some important concepts and distinctions for
volcanic systems include:
Magma is liquid rock found beneath the surface of the Earth.
Lava is liquid rock found on the surface of the Earth.
Igneous rocks form when magma or lava cools into a solid.
Volcanic rocks are igneous rocks that form on the surface (where cooling of lava is
rapid), and plutonic rocks are igneous rocks that form underground (where cooling of
magma is slow).
Plate Boundary Volcanoes:
(1) Divergent Margins
As two plates move apart, the space that was once occupied by the plates is replaced by
upwelling mantle asthenosphere. As this mantle material ascends, it experiences
decreasing pressures, which causes it to melt. This process is known as decompression
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