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1) TERMS – Plate- sections of the
lithosphere
Tectonics- “To build”, from
Greek
2) GRAND CANYON AND EARTH’S
HISTORY – rocks are recorded by carbon
dating and radioactive dating to show the
time periods of earth history which are
visible in the walls of the canyon
3a) EARTH’S AGE – 4,600,000,000 years
b) DATING TECHNIQUE – measuring
radioactive element decay such as
potassium
4a) WHAT THREE FACTORS PUZZLED
WEGENER? –* the fit of the continental
shorelines * identical mountains separated
by oceans
* identical non-marine fossils
separated by oceans
b) WHAT WAS HIS SOLUTION TO THESE
PUZZLES? – continents continually “drift”
c) WHAT DID WEGENOR COMPARE THE
MOVEMENT OF CONTINENTS TO? – the
movement of Greenland ice packs.
5) HOW HIGH IS THE MID-ATLANTIC
RIDGE? –1,000 to 1,200m (3,000 to 4,000ft)
6a) HOW LONG IS IT? – 60,000kms
b) WHAT ACTIVITY DID HESS TALK
ABOUT? – seafloor spreading
7) HOW LONG HAS IT TAKEN TO FORM
THE CURRENT ATLANTIC OCEAN? –
150,000,000 TO 200,000,000years
8) IN THE LAST 4,000,000 YEARS, HOW
MANY POLAR FLIPS HAVE OCCURRED? –nine
9) ON AVERAGE, HOW FAST IS THE
ATLANTIC SEAFLOOR SPREADING? –2.5cm/yr
10) HOW MANY PLATES IS THE
LITHOSPHERE DIVIDED INTO? –20
11) LIST THE FOUR WAYS PLATES
INTERACT WITH ONE ANOTHER? -*spread
apart, *grind past one another, *subduction
and *collision
12) WHY IS JAPAN AN EARTHQUAKE
PRONE AREA? –Japan is at the edge of the
collision (subduction) zone of the Eurasian
and Pacific plates
13) IN THE HIMALAYAN MTNS.WHAT HAS
CAUSED MARINE FOSSILS TO BE ELEVATED
29,000FT. ABOVE SEALEVEL? – India (which
is on the Indo-Australian plate) continues
to collide with the Eurasian plate thereby
elevating rocks and “their” fossils.
14) NAME THE FORCE THAT SUSTAINS
THE MOTION OF PLATE TECTONICS? convection cells of magma--- new magma
rises due to its intense heat level causing
older and colder magma to be pushed out of
the way and sink into the mantle where it is
melted and then flows toward the centre
ready to exit upward to the surface
completing the cell motion.
15) HOW LONG IS THE ESTIMATED TIME
FOR A UNIT OF MAGMA TO COMPLETE ONE
ROTATION THROUGH THE CELL? 500,000,000years
16A) WHAT IS A “HOTSPOT”? – a plume
of molten magma originating within the
mantle – it is not associated with or
generated by plate movements – hotspots
create volcanoes and islands when magma
spills onto the surface of the lithosphere –
there are 120 on earth’s surface
B) WHERE DOES ONE EXIST TODAY? –
Hawaii
17) WHY HAVE GIGANTIC QUAKES
OCCURRED IN MISSOURI, WHERE NO PLATE
BOUNDARIES EXIST? – as the Appalachian
mtns. erode sediment is dumped into
lowlands on both sides like in phase three of
our notes – weight builds up on the crust
there and it begins to sag – when it drops
under the force of excess weight, an
earthquake is the result – old faults are the
weak points in the rock structures where the
movement takes place – quakes are also
caused when the mountains snap upward
because the rock there is lighter due to the
fact less rock is present
18) MICRO PLATE TECTONICS – when
small plates collide with one of the 20 main
plates and “fuses” with the large plate –
thus the large plate is now larger
19) GROWTH OF NORTH AMERICAN
PLATE – by 25% due to micro plate tectonics
20) IN WHAT WAYS HAS PLATE
TECTONICS AFFECTED THE EARTH? -*builds
landforms, *influences climate, *creates
rocks, *creates ecosystems, *a role in
evolution
THE SOUTH AMERICAN GREEN TURTLE
“THE MARATHONER” (see map)
HER LIFE STORY OF TRAVEL:
*The South American green
(female) turtles swim to a distant island
(Ascension Is.) on the other side of the midAtlantic ridge to lay their eggs which has
saved the species from extinction due to an
absence of predators. *200,000,000 years
ago Ascension Is. was a mere 25 km. off the
coast of Brazil. To prevent the eggs from
being eaten by predatory jaguars, the lady
“marathoners” swam out to the island to lay
their eggs. Ascension Is. moves away from
the coast of Brazil at a rate of 2.5 cm/yr.
Thus the ladies have adjusted, such that
over the last 200,000,000 years they’ve
learned to swim 2,500 km. All of this effort
has saved the species from extinction.