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The
Geosphere
Lesson 3
Lesson 3
QUESTION:
Alfred Wegener (a German scientist) asked a question;
Do the coastlines of continents separated
today show evidence that they once matched?
If we went around the world and looked at all of the coastlines (on different continents) would we
see things that would make us believe they used to fit together (the continents).
ANSWER:
Yes, they do.
Wegener (and other scientists) found matching animal fossils on coastlines of
different continents and also matching geologic structures on different continents.
From that discovery he developed the:
“Theory of Continental Drift”
Wegener proposed the idea that once
upon a time all of the continents fit
together like a puzzle, and were one
massive continent called:
Pangaea
http://www.historyforkids.org/scienceforkids/geology/platetectonics/
Use the graphic organizer on “Discover” pg. 1 under the “Continental Drift”
tab to organize the information in the lesson:
**Use the letter Alfred Wegener wrote to fill in the organizer (on the same page).
Continental Drift
Continental Drift
Continental Drift
In the beginning Wegener was wrong about “how”
the plates moved from Pangaea to what we see
today. He later he developed a new idea called:
The Theory of Plate Tectonics
The Theory of Plate Tectonics
Use the interactive on “Discover” pg. 2, under the “Plate Tectonic Theory” tab to
investigate the evidence Wegener used to develop this theory.
Plate Tectonics
Plate Tectonics
Plate Tectonics
Plate Tectonics
Plate Tectonics
What’s the difference between them?!
Hotspots helped to support the theory of plate
tectonics.
The plate moves (very slowly) over a “plume” which is
releasing magma. As it cools it forms chains of islands.
What makes the plates move?
What makes the plates move?
“The asthenosphere of Earth acts like a conveyor belt moving slabs of
lithosphere.”
“Plates on Earth move as a result of convection deep within Earth.
Convection in the mantle of Earth results from the rising of hot rock
material and the sinking of cooler rock material. The constant rise and
fall of material leads to the formation of convection cells.”
Complete the interactive
on “Discover” pg. 2
“Mechanisms of
Movement” tab.
Convergent Boundary
• What happens with this type of plate
movement?
Convergent Boundary
The plates come together… converge.
This creates:
Convergent Boundary
The plates come together… converge.
This creates:
MOUNTAINS
or
TRENCHES
Divergent Boundary
What happens with this type of
plate movement?
Divergent Boundary
Plates move apart.
…diving away from each other.
Divergent Boundary
Plates move apart.
…diving away from each other.
This creates:
New crust is formed
A fault.
When the plates move horizontally (one moves one way the other moves the opposite).
What to do; Lesson 3
What to do; Lesson 3
What to do; Lesson 3
What to do; Lesson 3
Lesson 4
Lesson 4
The landscape of the Earth is formed and re-formed
over time. There are things that can impact the
geosphere and change it, such as:
Erosion
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Wind
Water
Freezing
Gravity
Earth's surface has interlocking plates known as tectonic plates, or lithospheric
plates.
“The movement of the plates breaks the crust in various locations known as faults.
A fault can, but does not necessarily, indicate the edge of a tectonic plate.”
Movement of Faults
The place where two segments of Earth’s crust come in contact
with each other at a fault is called the fault plane. The fault plane is
usually at an angle.
The hanging wall is
the block of rock
above the angle of
the fault plane.
The footwall is
the block of rock
below the angle
of the fault plane.
(*The location of the fault plane determines how each side of the fault is named.)
Movement of Faults
Normal Faults
Reverse Faults
Strike-Slip (Lateral) Faults
Movement of Faults
Normal Faults
Normal faults form as two segments of crust pull away from each other
at divergent plate boundaries.
The hanging wall drops down relative to the footwall, or the footwall moves up
relative to the hanging wall.
Normal faults form as a result of a type of stress known as tension stress.
Movement of Faults
Reverse Faults
Reverse faults are also known as thrust faults. These faults occur along
convergent plate boundaries, where lithospheric plates come together.
In a reverse fault, the hanging wall is “thrust” up—that is, it moves up relative
to the footwall.
Reverse faults form from a type of stress known as compression stress.
Movement of Faults
Strike-Slip (Lateral) Faults
Strike-slip faults, also known as lateral faults, occur where two blocks of crust
move past each other in opposite directions.
Strike-slip faults are common along transform plate boundaries, where
tectonic plates slide past each other.
Strike-slip faults form from a type of stress known as shear stress.
Mountains
Mountains result (are formed)
from the movement of tectonic
plates.
Mountains result (are formed) at
divergent and convergent
boundaries.
There are different types of mountains
that can form...
VOLCANOES
Forms when lava or ash build up to form into a mountain.
FOLDED MOUNTAINS
Formed when segments of Earth’s curst are bent and doubled over.
Gentle slopping sides
FAULT-BLOCK MOUNTAINS
Formed when stress causes pieces of the crust in a fault zone to be thrust
(pushed forcefully) upward.
Mountains with sharper/jagged edges, and steep cliffs.
Islands
There is land under the ocean,
(the ocean floor) and the
movement of the plates under the
water can give rise to ISLANDS
(and other structures).
An island is land that is completely surrounded by water.
An island is land that is completely surrounded by
water.
Islands form as a result of oceanic plates pushing
against each other (at a subduction zone).
“How?!” you ask…
A hotspot is a location when magma rises up through
the Earth’s crust to form volcanoes…
The oceanic plate moves (very slowly) over
a “plume” which is releasing the magma.
Because the plate is moving, as it cools it
forms a chain of islands.
Volcanoes that form over hotspots are known as shield
volcanoes.
Differences in Geological Areas:
FLORIDA
COLORADO
Differences in Geological Areas:
FLORIDA
- Flat land
COLORADO
- Mountains
Differences in Geological Areas:
FLORIDA
- Flat land
- Younger land
COLORADO
- Mountains
- Older land
Differences in Geological Areas:
FLORIDA
- Flat land
- Younger land
- Hasn’t experienced as much impact from weather (erosion)
COLORADO
- Mountains
- Older land
- Has experienced lots of impact from weather (erosion and
rebuilding)
“The process of mountain building takes time—
typically many millions of years.”
Geologic structures are constantly forming and reforming, but usually so slow that you wouldn’t notice
at all.
“Geologic structures build up as a result of processes
resulting from tectonic plate movement: volcanism,
folding, and faulting.”
What to do; Lesson 4
What to do; Lesson 4
What to do; Lesson 4
- Answer all questions and at the bottom check the box, and finally click “submit”.
Lesson 5
Lesson 5
Volcanoes are usually found where two tectonic plates meet (plate boundaries).
Remember some volcanoes can form at a hotspot (away from boundaries).
Usually volcanoes build mountains.
A volcano is any location where molten rock and other
materials make their way to Earth’s crust and onto the
surface.
Ring of Fire – No, it’s not really a ring with fire around it; it’s the most seismically and
volcanically active zone in the world. It surrounds the Pacific Ocean
Be sure the read the “text-only” to understand this better!
Types of Volcanoes
Cylinder cone:
Magma and ash shoot out and harden in the air, then pile up on
the sides creating the cone.
Stratovolcano:
These are formed from alternating eruptions; creating a
steep cone.
Shield Volcano:
Very wide slopes; usually form over a hot spot.
Lava Dome:
Really thick lava piles up as it exits the vent; usually
formed by one eruption.
Earthquakes
The upper part of the Earth’s crust is pretty breakable (they call
this brittle). When it is under “stress” from movements below
it can break; this is an earthquake.
Earthquakes
Earthquakes happen along boundaries (usually
transform boundaries). When the rock breaks
energy is released, this is called seismic energy
or waves.
“A seismic wave is any ground movement that results from energy released
during an earthquake. The point in the Earth’s crust where the rock ruptures is
the focus. The point on Earth’s surface directly above the focus is the
epicenter.“
Body waves:
Surface waves
Two types of body waves:
P waves:
S waves:
Body waves:
P-waves:
Primary waves or compression waves
Travel through the solid and liquid parts of Earth
Fastest earthquake waves
Always the first waves to appear on a seismogram
Cause ground to move horizontally back and forth through compression.
P-waves bounce off the liquid core.
Body waves:
S-waves:
Secondary waves or shear waves
Can travel through Earth’s solid portions only
When they hit the liquid core, S-waves are no longer able to be detected.
A shadow zone is created where earthquake waves are not detected
S-waves are absorbed at the core.
Cause ground to move back and forth in an S-shaped pattern
Two types of surface waves:
R waves:
L waves:
Surface waves:
R-waves (Rayleigh waves)
Cause lots of damage to the surface of the Earth, especially to
buildings
Have a rolling motion, like the waves of the ocean
L-waves (Love waves)
Cause lots of damage to the surface of the Earth, especially to
buildings
Have a side-to-side motion similar to the movement of a snake
Modeling Geologic Events
Scientists use models to help understand what will happen during a
geologic event, such as an earthquake or volcano eruption.
Creating a model allows them to attempt to see what type of damage could
occur as a result of one of those events and how intense the event could be.
What to do; Lesson 5
What to do; Lesson 5
What to do; Lesson 5
What to do; Lesson 5
What to do; Lesson 5
What to do; Lesson 5
What to do; Lesson 5