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Elaboration
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The theory of plate tectonics was finally accepted by the
scientific community in the 1960s, when further evidence had
accumulated in support of it. The theory was seen to provide
an explanation for a diverse array of seemingly unrelated
phenomena, and there was a scientifically sound physical
explanation of how such movement could occur.
Benchmarks10E3
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Specific Ideas
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- The idea of continental drift was suggested by the
matching shapes of the Atlantic coasts of Africa and
South America, but rejected for lack of other evidence.
It just seemed absurd that anything as massive as a
continent could move around. Benchmarks 10E1
- Early in the 20th century, Alfred Wegener, a German
scientist, reintroduced the idea of moving continents,
adding such evidence as the underwater shapes of the
continents, the similarity of life forms and land forms
in corresponding parts of Africa and South America, and
the increasing separation of Greenland and Europe. Still,
very few contemporary scientists adopted his theory.
Benchmarks 10E2
- From time to time, major shifts occur in the
scientific view of how the world works. More often,
however, the changes that take place in the body of
scientific knowledge are small modifications of prior
knowledge. Change and continuity are persistent features
of science. Benchmarks 1A2
- No matter how well one theory fits observations, a
new theory might fit them just as well or better, or
might fit a wider range of observations. In science, the
testing, revising, and occasional discarding of theories,
new and old, never ends. This ongoing process leads to an
increasingly better understanding of how things work in
the world but not to absolute truth. Evidence for the
value of this approach is given by the improving ability
of scientists to offer reliable explanations and make
accurate predictions. Benchmarks 1A3
- In the short run, new ideas that do not mesh well
with mainstream ideas in science often encounter vigorous
criticism. In the long run, theories are judged by how
they fit with other theories, the range of observations
they explain, how well they explain observations, and how
effective they are in predicting new findings.
Benchmarks1B6
- New ideas in science are limited by the context in
which they are conceived; are often rejected by the
scientific establishment; sometimes spring from
unexpected findings; and usually grow slowly, through
contributions from many investigators. Benchmark 1B7
- The solid crust of the earth--including both the
continents and the ocean basins--consists of separate
plates that ride on a denser, hot, gradually deformable
layer of the earth. The crust sections move very slowly,
pressing against one another in some places, pulling
apart in other places. Ocean-floor plates may slide under
continental plates, sinking deep into the earth. The
surface layers of these plates may fold, forming mountain
ranges. Benchmarks 4C4
- Earthquakes often occur along the boundaries between
colliding plates, and molten rock from below creates
pressure that is released by volcanic eruptions, helping
to build up mountains. Under the ocean basins, molten
rock may well up between separating plates to create new
ocean floor. Volcanic activity along the ocean floor may
form undersea mountains, which can thrust above the
ocean's surface to become islands. Benchmarks 4C5
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Developmental & Instructional
Implications
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The story of why science accepted the idea of moving
continents only after long resistance illuminates the
conservatism of the scientific enterprise. Contrary to the
popular public image of scientists as radicals ready to
discard their beliefs instantly in the face of contrary
"facts," the plate-tectonics episode shows that it sometimes
takes a large accumulation of evidence over an extended
period of time to provoke a dramatic shift in what most
scientists in a discipline accept as true. The history of
the rise of the theory of plate tectonics shows that the
acceptance of a theory depends on its explanatory power as
well as on the evidence that supports it. As it has turned
out, the modern theory of plate tectonics makes sense out of
such a large and diverse array of phenomena related to the
earth's surface that it now serves as a unifying principle
in geology. In a sense, plate tectonics does for geology
what evolution does for biology. Benchmarks p. 247
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