UNIT 4: THE EARTH’S CRUST Weathering and...
50
GRADE 7 SCIENCE UNIT 4: THE EARTH’S CRUST 11/12 Earth’s Crust is constantly changing Weathering and Erosion
Transcript of UNIT 4: THE EARTH’S CRUST Weathering and...
GRADE 7 SCIENCEUNIT 4: THE EARTH’S CRUST11/12Earth’s Crust is constantly changingWeathering and Erosion
Earth’s Structure - Layers of the Earth
Draw a labeled
Diagram
Layers of the Earth Rap’s
https://www.youtube.com/watch?v=Q9j1xGaxYzY
https://www.youtube.com/watch?v=RiHRI_Z2Kgs
Layers Of the Earth
1. Inner Core2. Outer Core3. Mantle4. Crust
Inner Core
Position: In the center of the earth (deepest)
Size: Second smallest
Description: Made of Solid iron and nickel
Outer Core
Position: Between the inner core and mantle
Size: Second thickest layer
Description: Made of liquid iron and nickel
Mantle
Position: Between the crust and outer core
Size: The thickest layer
Description: Partly Molten. Looks “plastic-like” (silly putty)
Crust
Position: On the outside of the earth
Size: The thinnest layer
Description: The Continental (land) crust is thicker than the oceanic (ocean floor) crust
The Crust - In detail
● The crust is broken into pieces (ocean and land crust)!○ These pieces are called Plates.
● The plates are always moving!
Plate Jigsaw activity!
Plate Tectonic Theory
How did we come to understand Earth Science?
Scientists and Technology!
Alfred Wegener
● Saw the continents fit like a puzzle
● He proposed the Theory of Continental Drift
Theory of Continental Drift
● A Theory that:○ the continents move○ There was a lot of evidence to support this
● Problem: There was no mechanism to cause the movement!
Pangea
The supercontinent made when all the continents were together
https://www.youtube.com/watch?v=cQVoSyVu9rk
4 pieces of evidence for continental drift
1. Continental fit: The continents seem to fit together (Africa and South America)
4 pieces of evidence for continental drift
2. Fossils: The same type of fossil are found on different continents (Canada and Europe)
4 pieces of evidence for continental drift
3. Rock layers: The same type of rock layers on different continents
4 pieces of evidence for continental drift
4. Climate: Coal that forms in warmer climate only is found in Antarctica!
Technologies Used in Earth Science
● Sonar● Magnetometers● Deep sea drilling
● Magnetometer paper
activity
Remember!
Although there was a lot of Evidence -
There was no accepted mechanism
(No force that caused the continents to drift)
So… Continental Drift was rejected!
Plate Tectonics
● New technology and data were found!
The theory of continental drift became the Plate Tectonic Theory
Theory of continental Drift to Plate tectonics video
1:22 - 10:15
https://www.youtube.com/watch?v=HrKTuCDierM
Plate Tectonics
Plate: each pieces of the Earth's crust
Plate Boundary: The edges of plates. Where two plates meet
The Driving Force Behind Theory of Plate Tectonics
Convection Currents: the heated rock in the mantle rises then cools and sinks. This moves the plateshttps://www.youtube.com/watch?v=ryrXAGY1dmE
3 Types of Plate Boundaries
1. Divergent
Description: When the plates move away from one another
Force: Pulling apart
Results: Volcanoes and earthquakes
3 Types of Plate Boundaries
2. Convergent:
Description: When the plates move toward each other
Force: Pushing together
Results: Volcanoes, earthquakes and mountains
3 Types of Plate Boundaries
2. Transform:
Description: When the plates move alongside each other
Force: sliding past
Results: Earthquakes
3 plate boundaries video
https://www.youtube.com/watch?v=0mWQs1_L3fA
Canadian Earth Scientists!
J. Tuzo Wilson - proposed the third type of plate movement - Transform boundaries!
Canadian Earth Scientists!
Joseph Tyrrell - discovered dinosaur fossils in Alberta,
● It proved that the local climate was warmer at an earlier time.
Canadian Earth Scientists!
Harold Williams - (Newfoundlander!) highlighted that plate tectonic activity happened on the eastern edge of North America.
Catastrophic Events from plate boundaries!
Earthquakes and Volcanoes!
Discussion questions
1. Do earthquakes and volcanoes occur in NL?
2. Is there evidence that Earthquakes or volcanoes occurred here in the past?
Earthquakes
Definition: The shaking of the earth
Caused by: The release of energy from plate movement in Earth’s crust.
When this energy is released, it travels in waves (seismic waves).
Example: Tsunami that hit burin peninsula
Seismograph
The device used to record earthquakes.
VolcanoesDescription: an opening in the Earth’s crust.
Caused by: Plate movement at boundaries
Example: Mount St. Helen’s in Washington D.C. - in the United States
3 Locations volcanoes form:
1. Convergent plate boundaries2. Divergent plate boundaries3. Hot spots
Volcanoes - 3 locations
1. Convergent plate boundaries
Description: Intense pressure melts rock that later flows to the surface as a volcano
Example: the Pacific Ocean is being subducted under Japan.
Volcanoes - 3 locations
2. Divergent plate boundaries
Description: Molten rock flows up to the surface
Example: The mid-Atlantic Ridge.
Volcanoes - 3 locations
3. Hot spots:
Description: Areas where the crust is thin magma can be forced up through the cracks
Example: The Hawaiian Islands.
Pattern of Earthquakes and VolcanoesOccur mostly along the ‘ring of fire’ (along plate boundaries!)
Past Theories for Volcanoes & Earthquakes
Pele: The Hawaiian goddess who makes the mountains shake and lava flow at Kilauea, Hawaii
Glooscap: Mi’kmaq legend about how Glooscap (the first man) turned a beaver into the Sugarloaf Mountains.
Weathering and Erosion
How could these rock formations occur?
Weathering
The mechanical and/or chemical breakdown of rock.
There are 2 Types:
1. Chemical2. Mechanical
1. Mechanical Weathering
The physical breakdown of rocks into smaller fragments.
Examples:
a. Frost Wedge: Ice breaking apart the rock (most common)
b. Movement by plants/animals: burrowing through rock
2. Chemical Weathering
When chemical reactions break down rocks.
Examples:
a. Acid rain: the acid slowly breaks up the rock
b. Chemicals made by animals: lichens chemicals break down rock
Erosion
The process that loosens and moves weathered rock particles (sediment) over Earth’s surface
Agents of Erosion
1. Water in motion (most powerful)
2. Meteorological processes (rain and wind)
3. geological processes (gravity and glaciers)
Weathering Vs. Erosion - What's the difference?
Weathering Vs. Erosion - What's the difference?
Weathering breaks up the rock
Erosion moves the rock!
