1. Integrated Science One
Plate Tectonics

2. Main Layers of Earth Crust Mantle Core
Lithosphere includes the crust and upper mantle

3. 1. Crust This is the skin of the earth
Only between 8 and 67 kilometers thick
It is deepest beneath mountains
Oceanic crust is thinner and more dense than continental crust

4. Types of Crust
Oceanic crust is dense and found beneath the oceans and has a thickness of about 4-7km.
Continental crust is thicker and less dense and has an average thickness of approximately km.

5. 2. Mantle Beneath the crust Heavier than the crust
Between 2800 and 3000 km thick
Seems to be in a fluid state
Makes up about 80% of the Earth’s volume

6. 3. Core Beneath the mantle Made up of 2 parts
Outer core which contains melted iron and nickel
Inner core which is hot and solid

7. Differences in the 3 main layers
Crust and mantle are both made of hard solid rock, but the crust is less dense than the mantle.
The core is believed to be composed of iron and nickel

8. Alfred Wegener
He proposed that based on physical evidence from coastlines, rocks, and fossils the continents were all connected approximately 200 million years ago in a supercontinent called Pangaea.
This theory is called continental drift

9. One hypothesis states that plate movement results from convection currents in the asthenosphere
Asthenosphere – the zone of the mantle beneath the lithosphere that consists of slowly flowing solid rock

10. Plate Tectonics
Theory stating that crustal plates on the surface of Earth are continuously moving due to convection currents.
Types of movement of plates
Divergent
Convergent
Subduction
Transform fault

11. Occurances at boundaries of plates
Earthquakes
Volcanoes
Mountain formation

12. Divergent boundary Occurs where two plates move away from each other
Forms rift valleys in oceanic crust

13. Convergent Boundary
Where two plates move toward each other

14. Transform fault Occurs where two plates move past each other
Breakage of rocks along a fault line releases energy in the form of seismic waves producing earthquakes

15. Earthquakes Occur at transform faults
Seismograph measures how much the surface of Earth moves during an earthquake
Surface waves are the most damaging
Minimum number of seismograph stations needed to determine earthquake’s epicenter is three

16. More on Earthquakes
The magnitude of earthquakes is expressed using the Richter scale
The Richter scale expresses the relative magnitude of an earthquake, which is a measure of the energy released at the focus of an earthquake

17. Subduction zone
Zone where oceanic crust dives beneath continental crust
In subduction zones, when a denser plate dives into the mantle, the rock reaches its melting point and begins to melt and form magma – hot, low density magma rises to surface forming mountains and volcanoes

18. Volcanoes
A vent in Earth’s crust through which hot, liquid rock come to the surface
Magma released from volcanoes is molten rock from the mantle and crust

19. Volcanoes are common around the edges of the Pacific Ocean because as the Pacific Plate is subducted under surrounding plates, the Pacific Plate is forced into the mantle, where the rock melts and rises to the surface, creating volcanoes

20. Types of Volcanoes Shield – rich in magnesium and iron
Cinder – caused by large amounts of gas trapped in the magma
Composite – composed of many layers of cinders and lava

21. Rock Types Igneous – Sedimentary –
Metamorphic – changed by heat and pressure. Sedimentary can change into metamorphic

22. Igneous Formed from magma cooling
Those that have mineral crystals easily seen with the unaided eye formed intrusively (geode)

23. Sedimentary Formed by weathering
Named according to size of the fragments they contain
Can contain fossils
Limestone (a sedimentary rock) can be metamorphosed into marble

24. Metamorphic
Rocks that are changed by heat and pressure will form this type of rock
When heated, both igneous and sedimentary rock become metamorphic

25. Age of rocks
Superposition is used to determine the relative age of rocks
Radioactive isotopes are used to determine a more exact age of rocks

26. New evidence supporting theory of plate tectonics
Bands of rock with alternating magnetic polarities were discovered on either side of the Mid-Atlantic Ridge in the 1960s. As the youngest rock appears near the center of the ridge and the oldest rock appears further away, this suggests that the oceanic plates are moving away from the plate boundary

27. Weathering of rocks
Physical weathering does not alter the chemical compositon of rock
Water is the most effective agent of physical weathering and erosion
The process in which sediment is laid down is called deposition

28. Weathering A. Physical - breaks rock into smaller pieces 1. ice
2. plants
B. Chemical
1. carbon dioxide dissolved in water can dissolve rock
2. acid rain can dissolve minerals

29. Essay Questions – choose 1
How does a seismograph work?
The Himalayas are a mountain range in India that continues to increase in both width and height. Describe the type of plate boundary found in this region and explain the reason behind the formation of the mountain range

30. Erosion
II. Erosion - process by which rock and /or the products of weathering are removed.
A. Water
B. Wind
C. Glaciers

31. How do seismograms recorded during earthquakes help scientists learn about the composition of Earth?
In an earthquake-prone area, which earth material – igneous rock or sedimentary rock – would be better for constructing buildings? Explain your answer.