Transcript Lesson 1: Earth Energy Lesson

Geology!
Like Rocks and Stuff…
What is Geology?
• The study of the “Physical”
World and it’s natural
processes.
• Earth’s History!
Why Do we care?
What do Geologists study?
Earthquakes
Rocks and Minerals
Fossils/Earth History
Volcanoes
Erosion
So let’s look at an Earth History
problem:
Alfred Wagener noticed that several continents seem to fit
together really well (like pieces of a puzzle)
For example: Africa and South
American’s coastlines almost
Look made for each other…
In fact, lots of the continents seem to fit together like
a HUGE puzzle! Is it just a coincidence?
None of these organisms are ocean living organisms capable of swimming for
Thousands of mile. So how did their fossils get so wide spread?
• Also the fossils of the exact
same critters were found on
two different continents. THAT
WERE SEPARATED
Fig. 2.05 BY AN
OCEAN!!! yeah…that shouldn’t happen…
W. W. Norton. Modified from Motz.
So…
We have two big
Main
Concept
Wagener
phenomenon that
One: that
reasoned
are difficult to
All
the
all
of
the
explain:
continents
1)That the continents
look like giant
used
be
must to
have
pieces of a puzzle. joined together
been
joined
2) Fossils of the same
in
one
large
together
at
non-swimming
organisms found on piece
somecalled
past
land separated by an
“Pangea”.
time!!!
Wagener's
So…think:
No really! What
THINKforce
for ais
Problem:
How do you
an entire
minute….
strong get
continent to
move?
Don’t enough
just givetoup
move
and
click
entirethrough!
continents?
THINK!!!
What force could be strong
enough to move an entire
continent?
In fact, Wagener’s ideas were rejected at first because nobody
could believe there was a force strong enough to move an
entire continent…but then the answer was discovered!
So which form of energy makes the
Earth’s continents move about?
Heat Energy!
Main Concept Two:
Heat deep in the center of the earth (the
Core) creates enough force to drive the
process of change on the surface.
Remember your layers of the Earth
(from 7th grade):
• Inner Core
– Solid
• Outer Core
– Liquid
• Mantle
– Soft Solid
• Crust
– Continental (land)
– Ocean
Heat energy is what makes
motion and change on the Earth’s surface!
We already know that when fluid is heated,
it moves in a circular motion:
“CONVECTION”
What is Happening below the
earth’s surface?
Convection within the Mantle!
Notice that the rock in the
Mantle begins to move in
A circular motion = Convection!
VERY SOFT
ROCK
Primary Source of
Heat Energy
VERY SOFT
ROCK
As the mantle moves around, the crust “floating” on top of it
is “deformed” into different shapes and features!
These features include: Mountains, valleys, canyons,
volcanoes, oceans, deep sea trenches, etc…
Fig. 2.06b
W. W. Norton
So how do we get these different
features from mantle movement?
• http://education.sdsc.edu/optiputer/flash/c
onvection.htm
• Watch what happens as:
– Continents collide. (What is formed?)
– Continents “drift” apart. (What is formed?)
Since Wagener’s day we have observed new
evidence/phenomena that helps to support his
idea that the continents are indeed moving:
Some are found on the next few slides…
This is an image of the Atlantic Ocean bottom.
The ages of rocks are shown by colors.
Reds and oranges
are the youngest
Blues and greens
are the oldest
Evidence #1:
We have
discovered that
the age of rocks
on the sea floor
change as you
move away
from the middle
of the oceans.
The youngest
rocks are in the
middle; the
oldest are at the
edges.
Evidence #2: Locations of Earthquakes and
Volcanoes infer big cracks in the crust!
We call the pieces of crust : “Plates”
These “plates” act like floating rafts on the mantle
Evidence #3: We have used GPS technology
to actually track the movement of land. The arrows show
where the areas are currently moving.
There is more evidence, but these three are very convincing!
Motion of Plates
Where the “plates” touch each other, they form
three types of cracks/edges that we call:
“boundaries”:
*Divergent: Where two plates move apart
*Convergent: Where two plates collide into
each other
*Transform: Where two plates slide past
each other.
Divergent Plate Boundary
-Most common in the middle of oceans (mid-ocean ridges) In fact,
scientists think this is how new oceans are formed!
-Two plate moving apart from each other
-Many small Volcanoes
-Many small earthquakes
A?
B?
C?
Two plates diverging!
Which group of
volcanoes is
probably
older?
A: C
is the oldest!
And the old rock is on the outer edge
Notice that the young
rock is right down the middle
This group of volcanoes
used to be closer to the
Mid-Ocean Ridge!
The red colors shows the youngest rock
and the blue colors show the oldest rock!
Convergent Plate Boundary
-Where two plates collide with one another
-Most common at the edge of oceans
-Few, very large earthquakes
-Large volcanoes/ mountains form nearby (tallest places on earth)
-Deep sea trench (deepest places on earth)
What is all this white
A: Snow on Mountains
stuff on top of?
What are all these little islands?
A: Volcanoes!
A: What
A deep
is trench!
this
dark long feature?
Ocean Plate colliding with Continental Plate
Continental Plate colliding with Continental Plate
Why is there no trench?
A: Neither plate is going down!
What
here?
A: has
Veryformed
tall mountains!
Will you find volcanoes here?
A: Probably not. There is no
crust being melted
Transform
Plate Boundary
Transform Plate Boundary
-Most common between the other plate
boundaries.
-Two plates moving side by side
-“Offset” features
“Offset” help
river identify movement
-Common medium sized earthquakes