Leaving aside the record of paleontology, if the theory of Plate Tectonics
teaches us anything it is that Earth history is necessarily long duration,
something to measure in multiples of millions of years, indeed,
into the low billions of years.
I thoroughly enjoy ancient history and love to read etiologies -stories
that are intended to explain phenomena that are important in human lives.
I am enchanted by the naive legends of Mesopotamia especially, since in
them
we see the first civilized human beings seeking to understand the world
around
them in rational ways -even if their rationality is removed from our's by
5000 years of history. The stories of creation in the Bible also fall into
this
category for me, since, after all, many are directly derivative of
Mesopotamia
and, in any case, are highly creative and -for sure- have withstood
every
conceivable test of time as vehicles to express eternal truths --in a
similar
way to which Shakespeare does so also.
But just as no-one demands that all of Shakespeare must be flawless
and accurate scientifically -he seems to have believed in ghosts, for
instance-
exactly why should we make this demand for the Bible ? It does not make it
for itself and from every indication this is a doctrine that was imposed on
it
centuries after the canon was completed, presumably in the 300s AD.
In any case, to reject evolution is no different than rejecting all
relevant science
and all of the research, hard evidence, and solid calculations of science
that have been produced in the years since, say, 1700 AD.
Genesis is priceless, it is a cultural legacy for all humanity. Its value
is incalculable.
In general, people who don't know the Bible, really know it, not simply
have
second hand knowledge of a few stories from it, are culturally
impoverished.
However, what must be added is that people who don't know science,
really know it, not just know a few facts about it that are popular in
public education, are intellectually impoverished and miss out on
incredible riches in knowledge.
Billy
========================================
from the journal: Nature
Earth science: How plate tectonics clicked
* _Naomi Oreskes_
(http://www.nature.com/news/earth-science-how-plate-tectonics-clicked-1.13655#auth-1)
_1_
(http://www.nature.com/news/earth-science-how-plate-tectonics-clicked-1.13655#a1)
04 September 2013
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.
By 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 published_1_
(http://www.nature.com/news/earth-science-how-plate-tectonics-clicked-1.13655#b1)
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 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 drift_2_
(http://www.nature.com/news/earth-science-how-plate-tectonics-clicked-1.13655#b
2) . Holmes's 1944 textbook Principles of Physical Geology (Thomas Nelson
& Sons) was an introduction to the subject for many students.
(http://www.nature.com/news/501027a-i2-jpg-7.12148?article=1.13655)
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.
ELLIOT LIM/CIRES/NOAA/NATL GEOPHYS. DATA CENT.
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 the origins of
Earth's magnetic field, they discovered that magnetic minerals pointed in
different directions at different times in geological history, as if the
positions of the 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_
(http://www.nature.com/news/earth-science-how-plate-tectonics-clicked-1.13655#b3)
, 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 work_4_
(http://www.nature.com/news/earth-science-how-plate-tectonics-clicked-1.13655#b4)
. 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 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 globe_5_
(http://www.nature.com/news/earth-science-how-plate-tectonics-clicked-1.13655#b5)
.
In 1965, Canadian geologist Tuzo Wilson proposed a type of 'transform'
fault to accommodate the spreading sea floor around mid-ocean 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 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
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.
------------------------------------------
Journal name:
Nature
Volume:
501,
Pages:
27–29
Date published:
(05 September 2013)
--
--
Centroids: The Center of the Radical Centrist Community
<[email protected]>
Google Group: http://groups.google.com/group/RadicalCentrism
Radical Centrism website and blog: http://RadicalCentrism.org
---
You received this message because you are subscribed to the Google Groups
"Centroids: The Center of the Radical Centrist Community" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/groups/opt_out.
