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Questions 43-52 are based on the following
passage and supplementary material.
This passage is adapted from Angus Chen, “ The Dawn of
Plate Tectonics.” ?2014 by American Association for the
Advancement of science.
A journey to the Mariana Trench, the deepest
crevice on Earth ’ s surface, reveals the great Pacific
tectonic plate descending deep into the planet where
it recycles back into mantle rock. This recycling of
old tectonic plate, called subduction, drives plate
tectonics and is nothing new to scientists, but exactly
when the process got started is a hot debate. A new
study may put that to rest by unmasking a sequence
of 4.4-billion-year-old lavas as the remnants of the
first subduction zone on Earth. If correct, the
discovery marks the dawn of plate tectonics and thus
several geological processes critical to Earth ’ s
environment and perhaps even its life.
In 2008, scientists studying ancient lavas in
northern Quebec, known to geologists as the
Nuvvuagittuq greenstone belt, saw that they had the
same geochemical signature as lavas from modern
subduction zones like the Mariana. This meant that
they must have mixed with briny fluids squeezed up
through subduction zones and only there. The
geochemistry of those rocks could be used as a sort of
fingerprint to help identify subduction zone lavas.
Geologists Tracy Rushmer and Simon Turner of
Macquarie University in Sydney, Australia, decided
to take a closer look. They and their colleagues
noticed a distinct chemical pattern to the layers in
the lava, creating a unique sequence of rocks.
The team thought this sequence could be similar to lava
sequences made by modern subduction zones
like the Mariana Trench. Mark Reagan, a geologist at
the University of Iowa who has taken submersibles into
the trench five times as deep as 6500 meters,
confi rmed Rushmer and Turner ’ s suspicions.
“The whole sequence,” Rushmer says, “ linked in with
what Mark was seeing in the Mariana Trench.”
The team says each rock layer in the sequence at the
Mariana lavas and the Nuvvuagittuq lavas describes a
step in the birth of a subduction zone.
The key is in how rocks and their chemistry
change with each successive layer. As the oceanic slab
descends, magma begins rising up and erupts on the
surface in layers atop one another, creating a rising
sequence of igneous rocks. With increasing depth,
heat and pressure begin squeezing different elements
out of the slab in fluids. Over time, these fluids
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change the chemical composition of the lavas so
that they become rich in rare earth elements like
ytterbium, but poor in the element niobium. The fi rst
layer in the sequence erupts before the fluids can
escape the slab, but the next layer in the sequence
gets just enough fluid to make a partial signature.
The final layer carries huge amounts of rare earth
elements and very little niobium, together making
the clarion mark of subduction zone lava.
The team realized not only do both rocks carry
the same geochemical signature, but in comparing
the Mariana and Nuvvuagittuq, they also discovered
the rocks and the geochemistry of both sequences
change in the exact same way. This finding bolstered
the theory that the Nuvvuagittuq sequence is an
ancient subduction zone. “ Seeing the evolving
chemical signature,” Turner says, “ was much more
robust than just saying there is or isn ’ t niobium.”
Geochemist Julian Pearce of Cardiff University in
the United Kindom still isn ’ t completely convinced,
though. He says the Nuvvuagittuq greenstone belt
might just be too old and warped to have a reliable
signal from 4.4 billion years ago. “The evidence
would be compelling if the rocks were young,
undeformed, and fresh,” Pearce says. As they are
now, the Nuvvuagittuq rocks have been modified by
intense heat and pressure “ which can mask and
modify geochemical signal ” though contamination
from nearby rocks. Furthermore, while Pearce
believes a subduction zone is one place these
geochemical signatures can be made, “ it is not the
only location.”
While those are legitimate concerns, geoscientist
Norman Sleep of Stanford University in Palo Alto,
California, isn ’ t too bothered. “ It ’ s not fully sorted
out yet,” Sleep says, but the Nuvvuagittuq rocks
“ really seem like modern arclike lavas ” found at the
Mariana. When it comes to the geochemical
signature of subduction, Turner and the members
of the team say that heat and pressure don ’ t alter the
geochemical fingerprint much, and Sleep says this is
reasonable. Despite all of the difficulties of studying
such timeworn rocks, he says “ the work done in this
paper is very valuable.”
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Its
Adapted from E.J. Dionne Jr., "A Call for National Service" ? 2013 by
the Washington Post Originally published July 3 rd, 2013
Here is the sentence in the Declaration of Independence we always remember: “ We hold
these truths to be self- evident, that all men are created equal, that they are endowed by
their Creator with certain unalienable Rights, that among these are Life, Liberty and the
pursuit of Happiness.”
And here is the sentence we often forget: “And for the support of this Declaration, with a
fi rm reliance on the protection of Divine Providence, we mutually pledge to each other
our Lives, our Fortunes and our Sacred Honor.”
This, the very last sentence of the document, is what makes the better-remembered
sentence possible. One speaks of our rights. The other addresses our obligations. The
freedoms we cherish are self-evident but not self-executing. The Founders pledge
something “ to each other,” the commonly overlooked clause in the Declaration ’ s final
pronouncement.
We find ourselves, 237 years after the Founders declared us a new nation, in a season of
discontent, even surliness, about the experiment they launched. We are sharply divided
over the very meaning of our founding documents, and we are more likely to invoke
the word “ we” in the context of “ us versus them ” than in the more capacious sense that
includes every single American.
There are no quick fixes to our sense of disconnection, but there may be a way to restore
our sense of what we owe each other across the lines of class, race, background — and,
yes, politics and ideology.
Last week, the Aspen Institute gathered a politically diverse group of Americans under the
banner of the “ Franklin Project,” named after Ben, to declare a commitment to o ffering
every American between the ages of 18 and 28 a chance to give a year of service to the
country. The opportunities would include service in our armed forces but also time spent
educating our fellow citizens, bringing them health care and preventive services, working
with the least advantaged among us, and conserving our environment.
Service would not be compulsory, but it would be an expectation. And it just might
become part of who we are.
As you read the passage below, consider how E.J. Dionne Jr., uses
t evidence, such as facts or examples, to support claims.
t reasoning to develop ideas and to connect claims and evidence.
t stylistic or persuasive elements, such as word choice or appeals to
emotion, to add power to the ideas expressed.
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The call for universal, voluntary service is being championed by retired U.S. Army Gen.
Stanley McChrystal, in league with two of the country ’ s foremost advocates of the cause,
John Bridgeland, who served in the George W. Bush administration, and Alan Khazei,
co-founder of City Year, one of the nation ’ s most formidable volunteer groups. The trio
testifies to the non-ideological and nonpartisan nature of this cause, as did a column last
week endorsing the idea from Michael Gerson, my conservative Post colleague.
“ We’ ve a remarkable opportunity now,” McChrystal says, “ to move with the American
people away from an easy citizenship that does not ask something from every American
yet asks a lot from a tiny few.” We do, indeed, owe something to our country, and we owe
an enormous debt to those who have done tour after tour in Iraq and Afghanistan.
McChrystal sees universal service as transformative. “ It will change how we think about
America and how we think about ourselves,” he says. And as a former leader of an all-
volunteer Army, he scoffs at the idea that giving young Americans a stipend while they
serve amounts to “ paid volunteerism,” the phrase typically invoked by critics of service
programs. “ If you try to rely on unpaid volunteerism,” he said, “ then you limit the people
who can do it. . . . I ’d like the people from Scarsdale to be paid the same as the people from
East L.A.”
There are real challenges here. Creating the estimated 1 million service slots required
to make the prospect of service truly universal will take money, from government and
private philanthropy. Service, as McChrystal says, cannot just be a nice thing that well-
off kids do when they get out of college. It has to draw in the least advantaged young
Americans. In the process, it could open new avenues for social mobility, something the
military has done for so many in the past.
Who knows whether the universal expectation of service would change the country as
much as McChrystal hopes. But we have precious few institutions reminding us to join
the Founders in pledging something to each other. We could begin by debating this
proposal in a way that frees us from the poisonous assumption that even an idea involving
service to others must be part of some hidden political agenda. The agenda here is entirely
open. It ’ s based on the belief that certain unalienable rights entail certain unavoidable
responsibilities.
Write an essay in which you explain how PE.J. Dionne Jr. builds an argument to
persuade his audience that national service should be called for. In your essay,
analyze how Dionne uses one or more of the features listed in the box above (or
features of your own choice) to strengthen the logic and persuasiveness of his
argument. Be sure that your analysis focuses on the most relevant features of the
passage.
Your essay should not explain whether you agree with Dionne ’ s claims, but rather
explain how Dionne builds an argument to persuade his audience.
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