Download Activity 2A- Plates and Gates

Activity 2A- Plates and Gates
Unit-2 Geosphere
Background Information for the Teacher
105
Activity
NSES
CLEP
In this hands-on
activity, learners create
a time line and explore
a story to show how
continental drift and
plate movement has
altered continent
location, ocean currents,
and therefore climates
over geologic time. The
story of octopus species
development around
Antarctica is used to
illustrate the change
in the climate as the
Drake Passage opened
up. With a continuous
ocean current blocking
Antarctica from heat
flowing from the lower
latitudes its climate
dramatically changed.
Std B: Heat moves in
predictable ways, flowing
from warmer objects to
cooler ones.
Std C: Although different
species might look
dissimilar, the unity
among organisms
becomes apparent from
the evidence of common
ancestry.
Biological evolution
accounts for the diversity
of species developed
through gradual
processes over many
generations.
Std D Lithospheric
plates on the scales of
continents and oceans
constantly move at rates
of centimeters per year
in response to movement
in the mantle.
Fossils provide important
evidence of how life and
environmental conditions
have changed.
2a: Earth’s climate is
influenced by interactions
involving the Sun, ocean,
atmosphere, clouds, ice,
land, and life. Climate
varies by region as a
result of local differences
in these interactions.
2b: Changes in ocean
circulation caused by
tectonic movements or
large influxes of fresh
water from melting polar
ice can lead to significant
and even abrupt changes
in climate, both locally and
on global scales.
3a: Individual organisms
survive within specific
ranges of temperature,
precipitation, humidity
and sunlight. Organisms
exposed to climate
conditions outside their
normal ranges must
adapt or migrate, or they
will perish.
3c: The distribution
patterns of fossils show
evidence of gradual as
well as abrupt extinctions
related to climate change
in the past.
4a: Climate can be
described for different
time intervals, such as
decades, years, seasons,
months, or specific dates
of the year.
CLEP
4d: Scientific observations
indicate that global climate
has changed in the past,
is changing now, and will
change in the future.
7e: Ecosystems on land
and in the ocean have
been and will continue to
be disturbed by climate
change. Animals, plants,
bacteria, and viruses will
migrate to new areas
with favorable climate
conditions.
ELF
Geosphere 1c:
Processes arising from
plate tectonics, such
as earthquakes and
volcanism, can have direct
and profound effects on
the other Earth systems.
Geosphere 3a: The
topography of the seafloor,
formed by plate tectonics
and sediment deposition,
affects the flow path of
deep ocean currents.
Geosphere 3b: The
topography of the land,
shaped by plate tectonics,
weathering, erosion and
sediment deposition,
affects the flow path of
atmospheric currents.
Activity 2A- Plates and Gates
Unit-2 Geosphere
NSES: National Science Education Standards (http://www.csun.edu/science/ref/curriculum/reforms/nses/index.html)
CLEP: Climate Literacy Essential Principles (http://www.climatescience.gov/Library/Literacy/)
ELF: Environmental Literacy Framework (www.andrill.org/education/elf)
For more information:
NASA animation of plates moving apart, similar to diagrams
http://www.nasa.gov/audience/forstudents/5-8/features/F_Earth_Has_Faults_prt.htm
http://oceanexplorer.noaa.gov/edu/learning/1_plate_tectonics/plate_tectonics.html#slide
Video of ice increase / decrease Antarctica
http://www.youtube.com/watch?v=mQwxa47x5VU
Megaleledone setebos-A shallow water species of octopus
found all around Antarctica and only
in the Southern Ocean. It is a close
relative of the deep sea species.
The specimen shown is a juvenile.
Adults reach a total length of nearly 1
meter. (about one yard)
To learn more:
Strugnell, J., Rogers, A.D., Prodöhl, P.A.,
Collins, M.A. & Allcock, A.L. (2008) The
thermohaline expressway: the Southern
Ocean as a centre of origin for deepsea octopuses. Cladistics.
24: 853-860.
Photo credit: M. Rauschert (M. setebos).
106
Activity 2A- Plates and Gates
Unit-2 Geosphere
Background Information for Teachers
The word tectonics comes from the Greek root "to build," and “plate”, which means a large slab. The two words
together, create the term plate tectonics, which refers to how the Earth's surface is composed of plates. The
Earth's uppermost layer of Earth’s crust is fragmented into about a dozen large and small plates that are
moving relative to one another as they float atop molten material below. As people began to see the shape of the
continents on the Earth, they believed that the present-day positions were part of a preexisting larger landmass
termed supercontinents. Called Pangaea, this supercontinent was the birthplace of all the other continents and
began to break up between 225-200 million years ago (mya).
The idea that the continents moved over geologic time was largely developed by the German scientist, Alfred L.
Wegener, who suggested that the Earth's continents were once joined into supercontinents. In 1912, Wegener
stated that all the present continents were previously one large continent, but then broke apart due to shifting of
the landmasses. Two other viewpoints prevailed at this time, so Wegener’s thoughts were not readily accepted.
Many believed that the continents and ocean basins were unchanged since they formed. Others believed that the
Earth was slowly contracting and as this occurred, ocean floors became dry land, and dry land in turn became
ocean floor.
In the 1960s, the theory of plate tectonics began a change in the thinking about our Earth. The idea that the
Earth's surface is continually moving has profoundly changed the way we view our world. It took the work of
many scientists and technicians gathering data from many sources to confirm how the continents have been
shaped by plate-tectonic processes.
Wegener used the fossil record and similarity in rock layers as evidence. When Wegener presented the evidence
that the fossil plant Glossopteris was found on more than one disconnected land mass, this supported his theory
that the continents were once connected. In the 1960's, sequences of rock were discovered in Antarctica that
were similar to those on other continents confirming Wegener's theory. By the 1970's, a rapid growth of spacebased techniques for taking precise, repeated measurements provided more data for scientists to study the
movement of the plates.
Current plate movement can be measured by means of ground-based or space-based measurements. Geodesy
is the science of the size and shape of the Earth. Ground-based measurements are taken with conventional
and very precise laser-electronic instruments. However, because plate motions are global in scale, the best
measurements are satellite-based.
Space-geodetic measurements have already confirmed that the rates and direction of plate movement, averaged
over the several current years of data collection, confirm with rates and direction of plate movement averaged
over millions of years. Not all the plates move at the same rate. The African plate moves about 25 mm per year,
whereas the Australian plate moves about 60 mm per year.
107