Post on 24-Feb-2016
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Earth Science Chapter 5
Plate Tectonics
Big Ideas
• Earth’s Interior• Convection and the Mantle• Drifting continents• Sea-floor Spreading• Plate Tectonics
Earth’s Interior
•How far do you think it is to the center of the Earth?
•Almost 4,000 miles!•The deepest mine in the world is only 2 miles
•How do you think scientists know about the center of the Earth?
• Geologists use 2 main types of evidence to learn about Earth’s interior:–Direct Evidence from rock
samples–Indirect evidence from
seismic waves
Evidence from Rocks
• Humans have drilled holes and extracted rock from depths of 12 miles• Blasts from the Earth have
brought rocks from 100 ft to the surface
Evidence from Seismic Waves
• Earthquakes produce seismic waves• The speed of seismic waves
and the path they take show the structure of the planet
Three main layers
• The three main layers of Earth are the crust, mantle, and the core• These layers differ in size,
composition, temperature, and pressure
Temperature
• The first 20 meters beneath Earth’s crust is cool• After this depth, temperature
rises 1 degree Celsius per 40 meters• Heat comes from the molten
layer and radioactive substances
Pressure
•The deeper you go, the higher the pressure•This pressure is equal to that of a swimming pool
Pressure
Lab Skills Activity
• Work with a partner, • Read the directions to the Lab Zone Skills
Activity• Create the Data Table on page 129
Crust• Crust is a layer of rock that
forms Earth’s outer skin• Crust includes both dry land
and ocean floor• Crust is very thin compared to
the other layers of Earth, only 5-70 km thick
Crust
Crust
• The crust beneath the ocean is oceanic crust and usually made of basalt• Continental crust consists of rocks
such as granite
• I was very disappointed in the behavior of some of you on Friday.
• That was extremely disrespectful of you to run from the classroom when the bell rang.
• You need to remember that I dismiss you and not the bell.
• Please take your seat and sit quietly while you wait for class to begin
Mantle
• The mantle is about 40 km below the surface• It consists of a hot, solid rock• It can be divided into layers• The mantle is about 3000 km
thick
Mantle
Lithosphere
• The crust and the uppermost part of the mantle form the lithosphere• It is about 100 km thick• Lithos means “stone” in Greek
Lithosphere
Asthenosphere
• Under increase heat and pressure• Less rigid-soft like tar, but still
solid• Asthenes means “weak” in Greek
The Lower Mantle
• Beneath the asthenosphere the mantle is solid• This material extends to the
Earth’s core
Lower Mantle
The Core
• Consists of mostly nickel and iron• Made of two parts, a liquid outer
core and solid inner core• Together it is about 3486 km
thick
• Despite extreme pressure, the outer core is molten surrounding a dense, solid inner core• Evidence suggests that the extreme
pressure in the inner core will not allow the solid metal to spread and become liquid
Core
Core and Magnetic field
• Scientists think that movements in Earth’s liquid outer core create Earth’s magnetic field.• This magnetism is what attracts a
compass’ needle towards north (it aligns with Earth’s magnetic field)
Individually
• Complete the section 1 assessment on page 131, including the “writing in science” assignment. If you do not complete these in class, they will become your homework and will be due tomorrow.
Make a Chart
Types of Heat Transfer
Radiation
Explanation/definition
Conduction
Explanation/Definition
Convection
Explanation/Definition
When you complete the chart
• Read the sections “Convection Currents”, and “Convection Currents in Earth.”
• 1. Define Convection Currents• 2. Explain how convection currents work,
using a real example• 3. Create an illustration of a convection
current
Drifting Continents
• http://www.youtube.com/watch?v=WaUk94AdXPA
Continental Drift
• Prior to Columbus, mapmakers did not know about the new worlds• Shortly after they began to
notice how the coastlines of several countries seemed to fit together like a puzzle
Continental drift
• Early 1900s German Scientist Alfred Wegener made a hypothesis:• All of the continents were
once joined together in a single land mass and have since drifted apart.
The Origin of Continents and Oceans
• Wegener gathered evidence from different scientific fields to support his ideas about continental drift.• He studied land features, fossils,
and evidence of climate change
Write a Book!
• Make your own version of Wegner’s book• Use the same title as he did• Read pages 138-138 about the evidence he
found• Create a page for each type of evidence• Explain how the evidence supports his
hypothesis and include illustrations if appropriate.
• Page 1: Title• Page 2: Evidence from land
features• Page 3: Evidence from fossils• Page 4: Evidence from climate• Page 5: Conclusion