1. CHAPTER 2—the Dynamic Earth
Objectives
Describe the origins of earth
Identify and describe earths 3 major parts
Describe various nutrient cycles
Define weather and climate
Explain short and long term changes that happen on earth

2. 2.1 The Earth Forms Earthed formed about 4.6 b.y.a
The earth is solid (not gaseous) and is composed of 3 main layers:
Crust—solid continental plates made of rock and soil.
Lighter crust forms the continents
Heavier crust forms the ocean floors
Crust is broken into plates that move

3. 2.1 The Earth Forms Below the crust is the Mantle The Core
Made of molten (liquid) rock
There seem to be ‘hot spots’ in the mantle
Ex. Hawaii, Yellowstone
The Core
Solid outer core
Liquid inner core
The core is made of Iron and causes the earth’s magnetic fields.

4. 2.1 The Earth Forms Atmospheric beginnings
As the earth cooled, gases and vapors erupted and became the beginnings of the oceans and the atmosphere.
Meteors and comets battered the earth’s surface.
The environment was still not very conducive to life.
Still, tiny living things appeared on earth ~3.5 b.y.a.
Similar to today’s extremophyles.
Could withstand the conditions
How did this happen?? (discuss)

5. 2.1 The Earth Forms
About 2.7 b.y.a.—life forms appear that begin to change the planet
Cyanobacteria (blue-green algae) develop photosynthetic capabilities.
Oxygen becomes more prevalent in the atmosphere
Methane and Ammonia are removed from the atmosphere
Earth can then support a variety of different life forms.

6. 2.2 Land, Water, Air Objectives Describe effects of plate movement
Identify the main parts of the hydrospere
Identify the parts of the atmosphere
Describe benefits of the atmosphere

7. 2.2 Land, Water, Air Lithosphere—the land Hydrosphere—the water
Earth’s biosphere—where living things exist
Lithosphere—the land
Hydrosphere—the water
Atmosphere—the air

8. 2.2 Land, Water, Air LITHOSPHERE
Outer surface of the earth is covered by plates.
Continents
Ocean floor
Plate Tectonics—explains the mechanisms that cause the earth’s crust to move.
Volcanos
Rift valleys
Mountains
Continental Drift—theory that describes the movements of the plates

9. 2.2 Land, Water, Air Tsumani of Dec. 26, 2004 here
Mount Saint Helens here

10. 2.2 Land, Water, Air HYDROSPHERE Water layer of the earth
Oceans
Lakes
Streams
Ground water
Water vapor
Water is necessary to life
Aids in chemical reactions
Absorbs and holds (helps maintain a constant temp.)

11. 2.2 Land, Water, Air ATMOSPHERE—has 4 main layers
Troposphere—(0-16 km)
Where animals can live
Where weather occurs
Stratosphere—(16-50 km)
Ozone layer
Protects troposphere from UV rays
Mesosphere—(50-80 km)
Thermosphere—( km)
Has a layer of high temperature within it
Generally, as one increases elevation, temperature decreases

12. 2.2 Land, Water, Air
Will reflect some of the sun’s energy to prevent over heating (2000 F without it)
Will retain some heat to prevent too much cooling (-200 o F without it)

13. 2.3 cycles
Your brochures are due today.

14. 2.4 Climate and Weather Weather: What’s happening at the moment
Climate: long-term averages of weather conditions

15. 2.4 Climate and Weather What affects climate?
Latitude—distance away from the equator
Tropics, temperate and polar zones
Tilt of the earth (23.5o)
Results in seasons—solstice and equinox
Rotation of the earth
Coriolis effect – winds
Trade winds, prevailing westerlies, arctic easterlies.
Physical features
Mountains, oceans, lakes

17. Where are deserts?
Most deserts lie along the Tropic of Cancer and the Tropic of Capricorn. 
In desert regions, dry air currents blow across the land.  These dry air currents can blow hot or cold but they rarely carry rainclouds. 

19. 2.5 Changing Earth Continental Drift Erosion—wind, water.
Theory is that land masses move over geological time
Pangea—super continent that broke apart
Drift results in mountains, rifts
Erosion—wind, water.
Global Climate Change
Earth’s average surface temperature cycles
Humans have lived in a mild part of that cycle