1. Unit 2 – Earth’s Structure
Chapter 1 Introducing Earth

2. Key Words to Know System basalt Energy granite Atmosphere mantle
Geosphere lithosphere
Hydrosphere asthenosphere
Biosphere outer core
Constructive force inner core
Destructive force radiation
Seismic wave convection
Pressure density
Crust convection current

3. The Earth System
The earth system involves a constant flow of matter through different parts – ex: the water cycle
Rock too, cycles through the Earth System – ex: new rock can form from molten material inside Earth called magma. This material can rise to the surface and harden on land to form new rock.
The constant flow, or cycling of matter through the Earth system is driven by energy.

4. Parts of the Earth System
The Earth System has four main spheres: the atmosphere, the hydrosphere, the geosphere, and the biosphere. As a major source of energy for Earth’s processes, the sun can be considered part of the Earth System as well.
The four parts are interconnected.
One of the most important parts of the Earth system is – you!
Humans greatly affect the air, water, land and life.

5. Atmosphere Earth’s outermost layer is a mixture of gases – mostly
Nitrogen and oxygen. It also contains dust particles,
Cloud droplets, and the rain and snow.
It contains Earth's weather and is the cause for various climates

6. Geosphere Nearly all the Earth’s mass is found in Earth’s solid rocks
And metals.
The three main parts: metal core, solid middle layer and
Rocky outer core.

7. Hydrosphere About three quarters of Earth is covered by a relatively
Thin layer of water.
This is visible in oceans, glaciers, rivers, lakes, groundwater,
and water vapor.
Only a tiny part of the hydrosphere is fresh water.

8. Biosphere Life exists at the tops of mountains, deep underground,
At the bottom of the ocean, and high up in the atmosphere.
The parts of Earth that contains living organisms make up
The biosphere.

9. Feedback within a System
Feedback demonstrates how changes in one part of Earth might affect other parts.
Example: the feedback of melting glaciers affects the geosphere, hydrosphere and atmosphere.

10. Constructive vs. Destructive Changes
Lands are constantly being created and destroyed by competing forces.
The Himalayas are a result of the collision of two sections of Earth’s lithosphere, or Earth’s top layer of stiff, solid rock. The collision between the plates that carry India and the plates that carry China. Over millions of years these plates collided, and the process lifted up the ocean floor and formed the Himalayas.

11. Constructive Force
Forces that construct or build up mountains are called constructive forces. Constructive forces shape the lands surface by building up mountains and other landmasses. Ex: volcanoes

12. Destructive Forces
Destructive forces destroy and wear away landmasses through processes life erosion and weathering.

13. Lesson 2 – Earth’s Interior
Geologists have used two main types of evidence to learn about Earth’s interior: direct evidence from rock samples and indirect evidence from seismic waves.

14. Evidence from rock samples
Geologists have drilled holes as deep as 12.3 kilometers into Earth.
These samples give us clues on Earth’s structure and conditions deep inside Earth, where the rocks formed.
They can also re-create how rocks behave in laboratories to see how rocks behave.

15. Evidence from Seismic Waves
When earthquakes occur they produce seismic waves. Geologists record these waves and use them to study how they travel through Earth.
The speed of seismic waves and the paths they take can give clues about the structure of the planet.

16. What are the Features of Earth's Crust, Mantle and Core?
The three main layers of Earth are the crust, mantle, and the core.
These three layers vary greatly in in size, composition, temperature and pressure.
The deeper down inside Earth, the greater the pressure.
The temperature inside Earth increases as depth increases.

17. The Crust
The crust is a layer of solid rock that includes both dry land and the ocean floor.
The crust is much thinner than the layer that lies beneath it. In most places, the crust is between 5 and 40 kilometers thick.
The crust that lies beneath the ocean is called the oceanic crust and its overall composition is much like basalt, with small amounts of ocean sediments.
Continental crust, is the crust that forms the continents and contains many types of rock. But overall, its composition is much like granite.

18. The Mantle
The mantle is made of rock that is very hot, but solid. Scientists divide the mantle into layers based on the physical characteristics of the layers. Overall, the mantle is nearly 3,000 kilometers thick.
The lithosphere – the uppermost part of the mantle is brittle like rock, like the rock of the crust.
The Asthenosphere – below the lithosphere, the material is hotter and under increasing pressure.
The Mesosphere – beneath the asthenosphere, the mantle is hot but more rigid.

19. The Core The core is made mostly of the metals iron and nickel.
It consists of two parts – liquid outer core and solid inner core.
The inner core is a solid ball.
The other core is a layer of molten metal surrounding the inner core.

20. The Core and Earth’s Magnetic Field
Scientists think that movements in the liquid outer core create Earth’s magnetic field.
Because Earth has a magnetic field, the planet acts like a giant bar magnet; which affects the whole planet.
When you use a compass, the compass needle aligns with the lines of force in Earth’s magnetic field. Earth has magnetic poles and geographic poles

21. Geographic vs Magnetic Pole

22. Lesson 3 – Convection and the Mantle
Heat is constantly being transferred inside Earth and all around Earth’s surface.
There are three types of heat transfer
Radiation
Convection
Conduction

23. Radiation
The sun constantly transfers light and heat through the air, warming your skin.
Energy transferred through rays.

24. Convection The currents created as warm air rises from the ground.
Heat transfer by the movement of a fluid.

25. Conduction
Heat transfer between materials that are touching.

26. How does Convection occur in Earth’s Mantle?
Heating and cooling of a fluid, changes in the fluid’s density and the force of gravity combine o set convection in motion.
Without heat, convection currents eventually stop.
EX: When you heat soup on a stove, convection occurs in the soup. The soup at the bottom gets hot and expands to the top.

27. Convection currents in Earth
Heat from the core and the mantle itself causes convection currents in the mantle.
Convection currents like these have been moving inside Earth for more than four billion years.