1. Looking at the Earth CH.2

2. Earth
Earth is the fifth largest planet and the third from the sun (93 million miles away)
Liquid covers 71 percent of the Earth’s surface.
The Earth has one moon.
Measures 8,000 miles at the eaquator, shorter at the poles.

3. The major planets are, in order, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.

4. The Earth's Heights and Depths
The highest point on earth is Mt. Everest in Nepal.
Part of the Himalaya Range the peak is 29,035 feet above sea level
The Earth's Heights
and Depths

5. This sea is so salty that you actually float on the water.
The lowest point on dry land on earth is the shore of the Dead Sea in Israel at 1,349 feet below sea level.
The Dead Sea
This sea is so salty that you actually float on the water.
The minerals in the Dead Sea make rich mud that people believe has healing properties
The lowest point on the planet is the Mariana Trench under the Pacific Ocean at 35,827 feet below sea level.

6. Our generation is unique in its perspective of our planet
Our generation is unique in its perspective of our planet. From space, Earth looks small, finite and fragile.
What's the first thing that you notice about our planet when you see this image?
The Earth is composed of several integrated parts (spheres) that interact with one another:
atmosphere
hydrosphere
solid earth (lithosphere)
biosphere

7. The Earth System
Hydrosphere: the global ocean is the most prominent feature of our (blue) planet. The oceans cover ~71% of our planet and represent 97% of all the water on our planet.
Atmosphere: the swirling clouds of the atmosphere represent the very thin blanket of air that covers our planet. It is not only the air we breathe, but protects us from harmful radiation from the sun.

8. The Earth System
Biosphere: includes all life on Earth - concentrated at the surface. Plants and animals don't only respond the their environment but also exercise a very strong control over the other parts of the planet.
Solid Earth: represents the majority of the Earth system. Most of the Earth lies at inaccessible depths. However, the solid Earth exerts a strong influence on all other parts (ex. magnetic field).

9. The Earth System
This figure shows the dynamic interaction between the major spheres.
As humans, we desire to divide the natural world into artificial portions to make it easier. It should be stressed that these divisions are artificial.
What are some of the interactions between these spheres?

10. The earth consists of several layers
The earth consists of several layers. The three main layers are the core, the mantle and the crust. The core is the inner part of the earth, the crust is the outer part and between them is the mantle. The earth is surrounded by the atmosphere.

11. Earths Structure The Mantle
The layer above the core is the mantle. It begins about 6 miles(10 km) below the oceanic crust and about 19 miles(30 km) below the continental crust (see The Crust). The mantle is to divide into the inner mantle and the outer mantle. It is about 1,800 miles(2,900 km) thick and makes up nearly 80 percent of the Earth's total volume.
The Crust
The crust lays above the mantle and is the earth's hard outer shell, the surface on which we are living. In relation with the other layers the crust is much thinner. It floats upon the softer, denser mantle. The crust is made up of solid material but these material is not everywhere the same. There is an Oceanic crust and a Continental crust. The first one is about 4-7 miles (6-11 km) thick and consists of heavy rocks, like basalt. The Continental crust is thicker than the Oceanic crust, about 19 miles(30 km) thick. It is mainly made up of light material, like granite.

12. Earths Structure The core
The inner part of the earth is the core. This part of the earth is about 1,800 miles (2,900 km) below the earth's surface. The core is a dense ball of the elements iron and nickel. It is divided into two layers, the inner core and the outer core.
The inner core - the center of earth - is solid and about 780 miles (1,250 km) thick. The outer core is so hot that the metal is always molten, but the inner core pressures are so great that it cannot melt, even though temperatures there reach 6700ºF (3700ºC).
The outer - is about 1370 miles (2,200 km) thick. Because the earth rotates, the outer core spins around the inner core and that causes the earth's magnetism.

13. What are Earthquakes?
The shaking or trembling caused by the sudden release of energy
Usually associated with faulting or breaking of rocks
Continuing adjustment of position results in aftershocks
Earthquakes are a result of motion within the earth.
This only occurs where the earth is solid and therefore can only occur within about 100 miles of the surface
Earthquakes provide the best evidence regarding the interior structure of the Earth.

14. What is the Elastic Rebound Theory?
Explains how energy is stored in rocks
Rocks bend until the strength of the rock is exceeded
Rupture occurs and the rocks quickly rebound to an undeformed shape
Energy is released in waves that radiate outward from the fault

15. The Focus and Epicenter of an Earthquake
The point within Earth where faulting begins is the focus, or hypocenter
The point directly above the focus on the surface is the epicenter

16. Where Do Earthquakes Occur and How Often?
~80% of all earthquakes occur in the circum-Pacific belt
most of these result from convergent margin activity
~15% occur in the Mediterranean-Asiatic belt
remaining 5% occur in the interiors of plates and on spreading ridge centers
more than 150,000 quakes strong enough to be felt are recorded each year

17. The Economics and Societal Impacts of EQs
Damage in Oakland, CA, 1989
Building collapse
Fire
Tsunami
Ground failure

18. Volcanoes
Volcanoes are the result of hot spots within the crust or mantle of the earth.
The hot, liquid rock will break through weak spots in the surface and form volcanoes or flood basalts.
Many volcanoes do not release lava, instead they spit ash and small bits of lava called lapilli.
Some eruptions are quiet with very fluid (low viscosity) lava flows while others are explosive

19. Volcanoes
Quiet
lava
flows

20. Volcanoes

21. Volcanoes
Time lapse of the eruption

22. Volcanoes
Mt. St. Helen after the eruption

23. Volcanoes

24. Volcanoes

25. Volcanoes
Shield

26. Volcano locations