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PLATE TECTONICS ~ Birth of a Theory

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by

Leslee Siefert

on 1 November 2016

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Transcript of PLATE TECTONICS ~ Birth of a Theory

The Theory of Plate Tectonics
Terms
1-
lithosphere
- Earth's top layer with crust and upper mantle -- the tectonic plates
Terms - Formations
Terms - Formations
10-
folded mountain
- mountains formed by the lithosphere being compressed together

11-
rift valley
- a valley formed by lithosphere being pulled apart and sinking

12-
fault
-- a break or crack in the Earth's crust
Beginnings of an Idea
From
maps,
scientists noticed that some of the
continents
seemed to fit together like pieces of a
jig-saw puzzle
.
Beginnings of an Idea
Alfred
Wegener
developed a theory that at one time, all of the continents were once one large land mass -- he called this super-continent
Pangaea
.

(Pan =
many
gea =
land
)
Evidence
1 - plant and critter
fossils
Early Theory
Alfred Wegener proposed the
Theory of
Continental Drift
,
but did not know
why

the continents moved.

BUT .... the world was not convinced ... scientists needed a reason WHY the continents were moving.
Additional evidence
New Discoveries
FINALLY....

He discovered the

Mid-Atlantic Ridge
while plotting the ocean floor.

Harry Hess had discovered that the sea floor is
spreading
and
new
earth is being generated at the crack.

He also appreciated the fact that somewhere else in the world earth must also be being
destroyed
.
The answer to
WHY
the plates were moving was revealed.

Not drifting ... but being
pushed
or
pulled
by the movement of the mantle.
Princeton
University Geology professor,
Harry Hess
, became a
captain
an assault transport,
The USS Cape Johnson,
during WWII.

Technology aboard the ship that was designed to find German
U-Boats
(submarines) as well as help navigate the ship, was used to make a map of the bottom of the
Atlantic Ocean
.


2-
diverging
- moving apart
3-
converging
- moving together
4-
transform
- sliding past
5-
subduction
- one edge of a plate is pushed berneath another edge
6-
ridge
- chain of mountains that form a continuous, elevated crest (usually under the ocean)
7-
island arc

- chain of volcanoes that form islands in the shape of an arc
8 -
volcanic mountain chain
- a network of volcanoes forming a mountain chain
9-
trench

- a deep, narrow ditch on the ocean floor
2 - similar
rock
formations
3 - similar ancient
climates
On October 19, only three members of the expedition reached
Eismitte
. Since there was only enough supplies for the three at
Eismitte
, Wegener and Rasmus Villumsen (the remaining Greenalnder) took two dog sleds and headed back to the West camp. They took no food for the dogs and killed them one by one to feed the rest until they could run only one sled. While Villumsen rode the sled, Wegener had to use skis. They never reached the camp.
Six months later, on May 12, 1931, Wegener's body was found halfway between
Eismitte
and West camp. It had been buried (by Villumsen) with great care and a pair of skis marked the grave site. Wegener had been fifty years of age and a heavy smoker and it was believed that he had died of heart failure brought on by overexertion. His body was reburied in the same spot by the team that found him and the grave was marked with a large cross. After burying Wegener, Villumsen had resumed his journey to West camp but was never seen again. Villumsen was twenty three when he died and it is estimated that his body, and Wegener's diary, now lie under more than 100 metres (330 ft) of accumulated ice and snow.
September 24, 1930 – Three scientists were at a research camp
Eismitte
in Greenland. They were running out of supplies. Wegener set out with thirteen Greenlanders and a German Meterologist to supply the camp by dog sled. Conditions were so bad that twelve of the Greenlanders turned back to the West Camp.
Plate Tectonic Evidence
Sea Floor Spreading
Location of Volcanoes and Earthquakes
GPS Motion Tracking
Continental Drift may be gone ... but that still doesn't mean it's not a cool dance ...
Full transcript