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Writing Assignment One, Chapters 1 through 5Attached Files: assignment1-links.pdf (524.159 KB) geol100writing assgt1.pdf (170.288 KB)Essay Questions (100 points total).Note the attached PDF of this assignment…1. Explain thoroughly how it took 55 years (from 1915 until 1970) for the hypothesis of Continental Drift to develop into the theory of Plate Tectonics. Your answer should be no less than 500 words. (50 points)READ THIS! – In other words, use the theory of Plate Tectonics to show how the Scientific Method was used to “flesh out” the hypothesis of Continental Drift put forth by Wegener, by adding new data provided by new technology and people until general buy-in was obtained in 1970, when the term “Plate Tectonics” was coined. (Chapter 1, especially 1.3, The Nature of Scientific Inquiry; and Chapter 2, especially 2.1 through 2.3, and 2.9, “Testing the Plate Tectonics Model”). Do not spend time discussing what came before 1915! Wegener did a great job of laying out the evidence he had available at the time. After your introductory paragraph, I do not expect to see the name “Wegener” again.Be sure to explain:WHO were the key players?WHAT were the key observations and conclusions?WHERE were the observations made?WHEN were the key discoveries made?HOW were these discoveries accomplished, including fields of study, equipment, etc.?2. Use plate tectonic theory to explain the origin of Mount St. Helens (and by extension, the Cascades and all Andean-type mountains). Your answer should be no less than 500 words. (50 points)In your answer, include a discussion of:the plate tectonic process involvedthe origin of the magma and rocksthe composition of the magma and rocksthe type of eruptions that occur thereother geologic features associated with Andean-type mountains.For these questions, check the text and MasteringGeology Study Area (of course), and also study the links on the accompanying materials. It should go without saying that you should have successfully completed the Mastering Homework for the first five chapters.Important: know the meaning of the word PLAGIARISM – no plagiarism!Links for Writing Assignment 1, Geology 100Attached Files: PDF of Hali Felt PowerPoint (1.587 MB) PDF of How plate tectonics clicked (1.257 MB) PDF of When Continental Drift Was Considered Pseudoscience (91.08 KB)Links for Writing Assignment 1, Geology 100Part 1. Hypothesis vs. Theory — Continental Drift vs. Plate TectonicsFor starters, consider the following Smithsonian Magazine article from 2012, entitled When Continental Drift Was Considered Pseudoscience: http://www.smithsonianmag.com/science-nature/when-continental-drift-was-considered-pseudoscience-90353214/?allHere’s a recent perspective from Naomi Oreskes, Nature Magazine, entitled How plate tectonics clicked: http://www.nature.com/news/earth-science-how-plate-tectonics-clicked-1.13655 – printed on the 50th anniversary of the publishing of the definitive article on sea-floor spreading, by Fred Vine. Please listen to the Podcast, if you’d like!Let’s not forget Marie Tharp! Unfortunately, I didn’t seriously learn about her until I heard a Bob Edwards interview of Hali Felt, who wrote her biography, entitled Soundings – a fascinating read. Here are a few links you may find useful:Here’s a link to a New York Times video summarizing Marie’s obituary: http://nyti.ms/1cdkZlVHere’s a link to an hour-long talk by Hali Felt, at Columbia University: http://vimeo.com/53380314 and a link to a PDF of the PowerPoint used in the Hali Felt talk: http://online.geology-guy.com/pdfs/gebco_sixth_science_day_felt2.pdfAnd here’s a PDF of the obituary that started it all: http://online.geology-guy.com/pdfs/MarieTharp_NYT.pdfPart 2. Cascade Mountains (including Mt. St. Helens) — an example of Andean Plate Boundary I have a special affinity for this volcano, since I had volcanic ash fall on my head some 550 miles to the east, at the edge of Yellowstone National Park (itself a “super” volcano!). That was Sunday evening, 18 May 1980, before most of you were born, I assume. I was driving back from a geology meeting in Utah, where I had listened to talks by USGS scientists describing the volcanic activity which had just begun two months earlier. I had not heard that the Mountain had erupted, because there was no radio reception along the way, through the mountains of Utah, Idaho, Wyoming and Montana. I was quite surprised when ash began to fall from the sky and show up in my headlights!The Google Earth image above shows how far the volcanic ash traveled in about 12 hours! The red triangles on the map are active volcanoes, and the yellow dots are earthquakes that occurred in the previous week.USGS Publication: Eruptions of Mount St. Helens: Past, Present, and Future:Link: http://vulcan.wr.usgs.gov/Volcanoes/MSH/Publications/MSHPPF/MSH_past_present_future.htmlLinks to several videos which will give you more of a feel for the power that was released on May 18th, 1980!NOVA – Mt. St. Helens: Back From the Dead (not closed captioned, but a transcript is available in “Videos”) – http://www.pbs.org/wgbh/nova/earth/mt-st-helens.htmlthe following are closed captioned, on my YouTube channel (you’re welcome!)Eruption of Mount St. Helens, 1980 (released in 1981) – http://youtu.be/Jn52OAPK8nIMount St. Helens: May 18, 1980 (30th anniversary video) – http://youtu.be/_CrBp9KWY0oMount St. Helens: A Catalyst for Change – http://youtu.be/6g927Z54E0QThis link will take you to the part of the USGS Volcanic Hazards Program website that summarizes the major types of volcanic hazards: http://volcanoes.usgs.gov/hazards/ Note the links to the main types of volcanic hazards:Volcanic GasesVolcanic Gas and Climate ChangeAir PollutionSO2 AerosolsLaharsPyroclastic FlowsVolcanic LandslidesLava FlowsTephraPlate Tectonics VideosThis is a folder full of videos to help with your understanding of question 1 for assignment 1:Mt. St. Helens VideosLink to the folder under “Videos…” at left.May 18th 1980, 8:32 AMQuestions you’ll be asking…I can see clearly now – you’ll be wondering, in the very near future:when is this assignment due?where do I turn it in?what form should the document be in (and do I need to cite references, and should they be MLA, APA, GSA, etc.?)?All good questions, I’m sure… The answers:As it says in the syllabus, there is only ONE “due” date – the last day of the session. However, I would hope that you’ll get to work on this assignment as soon as you’ve finished the homework for the chapters specified, and get this assignment behind you according to the directions – word count, make sure the actual questions are answered…You’ll submit the document below, when I have made the link available. If it isn’t available yet, simply save your document on your computer or on a flash drive or your cloud drive, or… Hint: give the document a meaningful name, maybe including your name in the title, like “j-smith-geology-assgt1.pdf” for instance.The form it should be in is PDF attachment. You might have created it in Microsoft Word, Google Doc, Open Office Writer, or even Apple Pages, but convert your document to PDF (‘export to’, ‘save as…’, ‘convert…’). If you use someone else’s words in your report, that requires you let me know from whence they came. I’m definitely NOT an English instructor, but I’ll expect that in your citation, I should be able to find those words in the place you suggest, preferably with a single click of the mouse. And “google.com” or “wikipedia.org” is not a valid, specific reference.Before you turn in this assignment…Attached Files: Before you turn in this assignment.pdf (34.471 KB) Before you turn in this assignment, check your work – ask yourself:Have you finished the Mastering homework associated with the subject matter? (if you haven’t, I won’t grade it!)Did you check out the extra study material provided, such as videos and web links, etc.?Did you answer all parts of the questions?Are the essays of sufficient length (check the word counts in your word processor)?You should submit your work in Blackboard, as an attachment to the assignment.*** acceptable attachment format: Adobe Acrobat (PDF), period
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COMMENT
use for understanding cells that do not
communicate using electrical impulses.
It is this view that has perpetuated our
comparative ignorance about glia.
Moreover, the exclusion of glia from
the BRAIN Initiative underscores a
more general problem with the project:
the assumption that enough measuring
of enough neurons will in itself uncover
‘emergent’ properties and, ultimately,
cures for diseases1,4. Rather than simply
materializing from measurements of
“every spike from every neuron”1,4, better
understanding and new treatments will
require hypothesis-directed research.
The 302 neurons and 7,000 connections
that make up the nervous system of the
roundworm Caenorhabditis elegans were
mapped in the 1970s and 80s. More than
two decades later, little is understood
about how the worm’s nervous system
produces complex behaviours.
In any major mapping expedition,
the first priority should be to survey the
uncharted regions. Our understanding of
one half of the brain (the part comprised
of astrocytes, oligodendrocytes and
microglia) lags a century behind our
knowledge of neurons. I believe that
answers to questions about the brain and
public support for a large-scale study are
more likely to come from expanding the
search into this unknown territory. As a
first step, tools such as optogenetic methods and mathematical models are needed
to assess the number, distribution and
properties of different kinds of glial cell
in different brain regions, and to identify
how glia communicate with each other
and with neurons, and what developmental and physiological factors affect this.
This exploration into the ‘other brain’
must be done together with the proposed
studies of neurons. It cannot be achieved
as a by-product of them. ■
R. Douglas Fields is chief of the Nervous
System Development and Plasticity
Section at the US National Institutes of
Health in Bethesda, Maryland.
e-mail: [email protected]
1. Alivisatos, A. P. et al. Science 339,
1284–1285 (2013).
2. Kettenmann, H. & Ransom, B. R. (eds)
Neuroglia 3rd edn (Oxford Univ. Press, 2013).
3. Fields, R. D. The Other Brain (Simon &
Schuster, 2009).
4. Alivisatos, A. P. et al. Neuron 74, 970–974
(2012).
5. Schafer, D. P. et al. Neuron 74, 691–705
(2012).
6. Fields, R. D. et al. The Neuroscientist (in the
press).
7. Wake, H. Lee, P. R. & Fields, R. D. Science 333,
1647–1651 (2011).
8. Zatorre, R., Fields, R. D. & Johansen-Berg, H.
Nature Neurosci. 15, 528–536 (2012).
9. Han, X. et al. Cell Stem Cell 12, 342–353
(2013).
The US research vessel Explorer towed a magnetometer to map fields over the sea floor in 1960.
How plate
tectonics clicked
Fifty years after a paper linked sea-floor magnetic
stripes with continental drift, Naomi Oreskes explains
its legacy as a lesson in achieving scientific consensus.
B
y the time German geophysicist
Alfred Wegener proposed continental drift in 1912, palaeontologists had
long accepted that past connections between
now-separate lands explained the spread of
similar fossils and rock layers across them.
Geologists, too, knew of slabs of Alpine rock
that had been displaced hundreds of kilometres during mountain building.
But the arguments for continental motions
did not gel until the 1960s, when a drastic
expansion of geophysical research, driven
by the cold war, produced evidence that
reopened and eventually settled the debate.
One influential study was published1
in Nature 50 years ago this week. British
geologists Frederick Vine and Drummond
Matthews interpreted stripes of alternating
magnetic-field polarity in ocean bedrock as
evidence of a spreading sea floor that pushed
continents apart. Acceptance that large crustal
motions were a reality soon followed,
culminating in the theory of plate tectonics.
In its slow convergence of ideas and
evidence, the history of plate tectonics
holds lessons for today’s debates about
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ELLIOT LIM/CIRES/NOAA/NATL GEOPHYS. DATA CENT.
COMMENT
The age of ocean rocks increases (red to purple, 0–280 million years) with distance from ridges, where crust is formed, revealing the spread of the sea floor.
human-induced climate change. Although
science is always evolving, and our attention is drawn to controversy at the research
frontier, it is the stable core of ‘consensus’
knowledge that provides the best basis for
decision-making.
MANTLE CONVECTION
Wegener stands out because his solution
was close to the one that we now accept, and
because our individualist culture encourages
us to look for heroes to credit and discrete
events to celebrate. But he was not alone in
trying to explain commonalities in fossils
and rock strata. In the English-speaking
world, two of the most important players
in developing theories of continental-scale
crustal mobility were South African field
geologist Alexander du Toit and British
geochronologist Arthur Holmes.
Du Toit articulated the case in his aptly
named 1937 book Our Wandering Continents
(Oliver and Boyd). He acted as a clearing
house for geologists around the globe, who
sent him maps, rocks and fossils. Holmes,
working with the Irish geochemist John Joly,
suggested that crustal motion was driven by
radioactivity and the heat that it emanates,
advocating mantle convection as a means
of dissipating radiogenic heat and driving
continental drift2. Holmes’s 1944 textbook
Principles of Physical Geology (Thomas
Nelson & Sons) was an introduction to the
subject for many students.
The discussion was joined by Dutch geodesist Felix Vening Meinesz, who worked in
the 1930s in the Indonesian archipelago
and, with US geologists Harry Hess and
Maurice Ewing, in the Caribbean. Meinesz
found that Earth’s gravitational field was
weaker than normal above some of the
ocean’s deepest regions, which he explained
in terms of the buckling of low-density crust
into the mantle, dragged down by descending
convection currents, and he discussed these
ideas with Hess.
During the Second World War, Hess
found himself in the US Navy, fighting in
the Pacific theatre. He did not return immediately to tectonics after the war, but others
did, including several British geophysicists led
by P. M. S. Blackett and Keith Runcorn. In an
effort to understand
“More than
the origins of Earth’s
two dozen
magnetic field, they
discovered that magscientists
netic minerals pointed
did the key
in different directions
work that
at different times in
created the
theory of plate geological history, as
if the positions of the
tectonics.”
poles had changed.
Hess was drawn back to the topic after realizing that these ‘apparent polar-wandering
paths’ could be explained by the movements
of the continents.
OCEAN SPREADING
Hess suggested that rising mantle-convection
cells would drive apart the ocean floor above
them, increasing the separation of continents
to either side. The idea, which his colleague
Robert Dietz christened ‘sea-floor spreading’3, explained the old geological observations and the new geophysical ones, but it did
not gain immediate traction. That would take
further geomagnetic information.
Blackett, a socialist who opposed nuclear
proliferation, turned to geomagnetism after
the war to distance himself from military
work4. But military concerns — particularly
the demands of submarine warfare in the
atomic age — drove geophysical exploration
of the ocean floor, leading to the discovery in
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the late 1950s of sea-floor magnetic stripes.
The stripes were a surprise. In the report of
the discovery, oceanographers Ronald Mason
and Arthur Raff admitted to being at a loss
for an explanation. Others were less stymied.
Vine and Matthews, as well as Canadian geophysicist Lawrence Morley, independently
had the same idea. If the sea floor was spreading, then magnetic stripes would be expected:
rock formed at mid-ocean ridges would take
on Earth’s magnetic field, the polarity alternating as the field periodically reversed.
It was one thing to say that the oceans were
widening, another to link it to global crustal
motion. More than two dozen scientists,
including women such as Tanya Atwater and
Marie Tharp, did the key work that created
the theory of plate tectonics as we know it
— explaining continental drift, volcanism,
seismicity and heat flow around the globe5.
In 1965, Canadian geologist Tuzo Wilson
proposed a type of ‘transform’ fault to accommodate the spreading sea floor around midocean ridges, which was confirmed by US
seismologist Lynn Sykes. Other seismologists
demonstrated that in deep-ocean trenches,
slabs of crust were indeed being driven into
the mantle, and geophysicists worked out
how these crustal ‘plates’ move and relate to
the features of continental geology.
Vine and Matthews’ work is part of a
larger story of the growth of Earth science
in the twentieth century, made possible by
improved technology and greater governmental support after the Second World War.
Nearly all seismic and marine geophysical
data at the time were collected with military
backing, in part because of their cold-war
security significance.
This era marked a change in the character
of modern science. Research today is expensive and largely government-funded; almost
COMMENT
all major scientific accomplishments are the
collective achievement of large teams. This
reality — more prosaic than the hagiography
of lonely genius — reminds us that although
great individuals are worthy of recognition,
the strength and power of science lies in the
collective effort and judgement of the scientific community.
CONSENSUS MATTERS
J. R. CANN
In recent months, several of my colleagues in
climate science have asked me whether the
story of plate tectonics holds lessons for their
field in responding to those who disparage
the scientific evidence of anthropogenic
climate change. I believe that it does.
Many critics of climate science argue
that expert agreement is irrelevant. Science,
they claim, advances through bold individuals such as Wegener or Galileo Galilei
overturning the status quo. But, contrary
to the mythology, even Isaac Newton,
Charles Darwin and Albert Einstein worked
within scientific communities, and saw their
work accepted. In glorifying the lone genius,
climate-change dissenters tap into a rich
cultural vein, but they miss what consensus
in science really is and why it matters.
Consensus emerges as scientific knowledge
matures and stabilizes. With some notable
exceptions, scientists do not consciously try
to achieve consensus. They work to develop
plausible hypotheses and collect pertinent
data, which are debated at conferences, at
workshops and in peer-reviewed literature.
If experts judge the evidence to be sufficient, and its explanation coherent, they may
consider the matter settled. If not, they keep
working. History enables us to judge whether
scientific claims are still in flux and likely to
change, or are stable, and provide a reasonable
basis for action.
And maturity takes time. Scientific work,
compared with industry, government or business, has no deadline. Perhaps for this reason,
when Wegener died in 1930, according to
his biographers he was confident that other
scientists would one day work out how the
continents moved, and that this mechanism
would be along the lines of his proposal —
as indeed it was. Du Toit and Holmes were
similarly convinced.
The equanimity of these men speaks
to their confidence in science as a system.
They perceived what historian–philosopher
Thomas Kuhn articulated in The Structure of
Scientific Revolutions (University of Chicago
Press, 1962): that science is a community
affair and that knowledge emerges as the
community as a whole accepts it. A debate
comes to a close once scientists are persuaded
that a phenomenon is real and that they have
settled on the right explanation. Further discussion is not productive unless new evidence
emerges, as it did for continental drift.
Anthropogenic climate change has the
consensus of researchers. Political leaders
who deny the human role in climate change
should be compared with the hierarchy of
the Catholic church, who dismissed Galileo’s
arguments for heliocentrism for fear of their
social implications. But what of scientists who
in good faith reject the mainstream view?
Harold Jeffreys is an intriguing example.
An eminent professor of astronomy at the
University of Cambridge, UK, Jeffreys
rejected continental drift in the 1920s and
plate tectonics in the 1970s. He believed
that the solid Earth was too rigid to permit
mantle convection and crustal motion. His
view had a strong mathematical basis, but
it remained unchanged, even as evidence to
the contrary mounted.
If society had faced a major decision in
the 1970s that hinged on whether or not
continents moved, it would have been foolish to heed Jeffreys and to ignore the larger
consensus, backed by half a century of
research. As an early advocate of an immature
theory, Wegener was different. There were
substantial differences of opinion about crustal mobility among scientists in the 1920s. By
the 1970s, work such as Vine and Matthews’
study had brought consensus.
Fifty years on, history has not vindicated
Jeffreys, and it seems unlikely that it will
vindicate those who reject the overwhelming
evidence of anthropogenic climate change. ■
Naomi Oreskes is professor of the history of
science at Harvard University in Cambridge,
Massachusetts.
e-mail: [email protected]
Frederick Vine and Drummond Matthews (1970).
1. Vine, F. J. & Matthews, D. H. Nature 199,
947–949 (1963).
2. Oreskes, N. The Rejection of Continental Drift:
Theory and Method in American Earth Science
(Oxford Univ. Press, 1999).
3. Dietz, R. S. Nature 190, 854–857 (1961).
4. Nye, M. J. Blackett: Physics, War, and Politics in the
Twentieth Century (Harvard Univ. Press, 2004).
5. Oreskes, N. (ed.) Plate Tectonics: An Insider’s
History of the Modern Theory of the Earth
(Westview Press, 2001).
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Alfred Wegener, in Greenland, c. 1930, was ridiculed as having “wandering pole
plague.” (Alfred Wegener Institute, Germany)
By Richard Conniff
Smithsonian Magazine | Subscribe
June 2012
Six seismologists and a civil servant, charged with manslaughter for failing to predict a 2009
earthquake that killed 308 people in the Apennine Mountain city of L’Aquila, in Italy, will serve six
years in prison. The charge is remarkable partly because it assumes that scientists can now see
not merely beneath the surface of the earth, but also into the future. What’s even more
extraordinary, though, is that the prosecutors based their case on a scientific insight that was, not
long ago, the object of open ridicule.
[Editor’s Note: The story was updated on October 22, 2012, to reflect the decision.]
It was a century ago this spring that a little-known German meteorologist named Alfred Wegener
proposed that the continents had once been massed together in a single supercontinent and then
gradually drifted apart. He was, of course, right. Continental drift and the more recent science of
plate tectonics are now the bedrock of modern geology, helping to answer vital questions like
where to find precious oil and mineral deposits, and how to keep San Francisco upright. But in
Wegener’s day, geological thinking stood firmly on a solid earth where continents and oceans
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were permanent features.
We like to imagine that knowledge advances fact upon dispassionate fact to reveal precise and
irrefutable truths. But there is hardly a better example of just how messy and emotional science
can be than Wegener’s discovery of the vast, turbulent forces moving within the earth’s crust. As
often happens when confronted with difficult new ideas, the establishment joined ranks and tore
holes in his theories, mocked his evidence and maligned his character. It might have been the end
of a lesser man, but as with the vicious battles over topics ranging from Darwinian evolution to
climate change, the conflict ultimately worked to the benefit of scientific truth.
The idea that smashed the old orthodoxy got its start on Christmas 1910, as Wegener (the W is
pronounced like a V) browsed through a friend’s new atlas. Others before him had noticed that the
Atlantic coast of Brazil looked as if it might once have been tucked up against West Africa, like a
couple spooning in bed. But no one had made much of it, and Wegener was hardly the logical
choice to show what they had been missing. He was a lecturer at Marburg University, not merely
untenured but unsalaried, and his specialties were meteorology and astronomy, not geology.
But Wegener was not timid about disciplinary boundaries, or much else. He was an Arctic explorer
and a record-setting balloonist, and when his scientific mentor and future father-in-law advised
him to be cautious in his theorizing, Wegener replied, “Why should we hesitate to toss the old
views overboard?”
He cut out maps of the continents, stretching them to show how they might have looked before
the landscape crumpled up into mountain ridges. Then he fit them together on a globe, like
jigsaw-puzzle pieces, to form the supercontinent he called Pangaea (joining the Greek words for
“all” and “earth”). Next he assembled the evidence that plants and animals on opposite sides of
the oceans were often strikingly similar: It wasn’t just that the marsupials in Australia and South
America looked alike; so did the flatworms that parasitized them. Finally, he pointed out how
layered geological formations often dropped off on one side of an ocean and picked up again on
the other, as if someone had torn a newspaper page in two and yet you could read across the
tear.
Wegener called his idea “continental displacement” and presented it in a lecture to Frankfurt’s
Geological Association early in 1912. The minutes of the meeting noted that there was “no
discussion due to the advanced hour,” much as when Darwinian evolution made its debut.
Wegener published his idea in an article that April to no great notice. Later, recovering from
wounds he suffered while fighting for Germany during World War I, he developed his idea in a
book, The Origin of Continents and Oceans, published in German in 1915. When it was published
in English, in 1922, the intellectual fireworks exploded.
Lingering anti-German sentiment no doubt intensified the attacks, but German geologists piled on,
too, scorning what they called Wegener’s “delirious ravings” and other symptoms of “moving crust
disease and wandering pole plague.” The British ridiculed him for distorting the continents to make
them fit and, more damningly, for not describing a credible mechanism powerful enough to move
continents. At a Royal Geographical Society meeting, an audience member thanked the speaker
for having blown Wegener’s theory to bits—then thanked the absent “Professor Wegener for
offering himself for the explosion.”
But it was the Americans who came down hardest against continental drift. A paleontologist called
it “Germanic pseudo-science” and accused Wegener of toying with the evidence to spin himself
into “a state of auto-intoxication.” Wegener’s lack of geological credentials troubled another critic,
who declared that it was “wrong for a stranger to the facts he handles to generalize from them.”
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