1. Chapter 3 – The Dynamic Earth Section 1: The Geosphere
Describe the composition & structure of the Earth
Describe the Earth’s tectonic plates
Explain the main cause of earthquakes & their effects
Identify the relationship between volcanic eruptions & climate change
Describe how wind & water alter the Earth’s surface

2. The Earth as a System
Earth consists of rock, air, water, & living things that interact with each other
Divided into 4 parts:
AIR
WATER
LIVING THINGS
ROCK

3. The Earth as a System Geosphere Atmosphere Hydroshpere Biosphere
Solid portion consisting of rock
Extends from center of core to surface of crust
Atmosphere
Mixture of gases
Most found in first 30 km above Earth’s surface
Hydroshpere
All water on or near surface
Most is oceans
Biosphere
Where life exists
Extends from 9 km above surface to bottom of ocean

4. Discovering Earth’s Interior
Seismic waves used to study interior of Earth
Seismic waves
Travel through Earth’s interior during earthquakes
Altered by type of material they move
Changes in speed & direction measured when passing through different layers
Earthquake
Seismic wave

5. Composition of the Earth
Crust
Divided into three layers based on composition
Crust
Mantle
Core
layers become progressively denser toward the center
Core
Mantle

6. Crust Thin, outermost layer Solid, brittle
5 to 8 km beneath oceans
20 to 70 km beneath continents
Solid, brittle
Composed of lightweight elements
Makes up less that 1% of Earth’s mass

7. Mantle Layer between crust & core Composed of rock with medium density
Contains iron-rich minerals
Makes up 64% of Earth’s mass
Approximately 2900 km thick

8. Core Innermost layer Consists of densest elements
Liquid outer core
Super-heated molten lava
Composed of liquid nickel & iron
Solid inner core
Sphere of solid nickel & iron
Consists of densest elements
Radius approximately 3400 km
Solid inner core

9. The Structure of the Earth
Lithosphere
Divided into 5 layers based on the physical properties
Asthenosphere
Mesosphere
Outer Core
Inner Core

10. Lithosphere Composes crust & upper part of mantle
km thick (9-185 mi)
Divided into large pieces called tectonic plates
May be oceanic or continental
Slide on fluid portion of mantle
Movement can cause earthquakes

11. Asthenosphere Beneath lithosphere
250 km thick (150 mi)
Solid, plastic-like material of mantle
Made of rock that flows
Due to temperature & pressure
Allows for movement of tectonic plates

12. Mesophere Lower part of mantle
Lithosphere
Lower part of mantle
More solid & rigid than asthenosphere due to increased pressure
Can’t flow
Asthenosphere
Mesosphere
Outer Core
Inner Core

13. Outer Core Super-heated molten lava Source of Earth’s magnetic field
Composed of liquid nickel & iron
4000 to 9000 °F
Source of Earth’s magnetic field
Creates protective bubble
Deflects Sun’s solar winds

14. Inner Core Solid ball Composed of nickel & iron
9000 °F & 45,000,000 psi
Rotates in liquid outer core

15. Plate Tectonics Large, irregularly shaped slabs of rock
Composed of oceanic & continental lithosphere
Continental rocks
Lightweight minerals (quartz, feldspar)
Thicker crust
Oceanic rocks
Heavier, denser basltic rocks
Thinner crust

16. Major & Minor Tectonic Plates
Plates move in different directions and speeds, thus crash together, pull apart or side swipe each other like cars in a demolition derby

17. Plate Boundaries
Most geologic activity occurs where plates meet or divide (called boundaries)
Movement of plates creates 3 types of tectonic boundaries
Convergent – plates collide, move into one another
Divergent – plates move apart
Transform – plates move sideways in relation to one another
Movement of tectonic plates causes
Mountain formation
Earthquakes
Volcanic eruptions

18. Plate Tectonics and Mountain Formation
Plates collide, crust thickens
Rocks break & buckle
Continental plate folds into huge mountain
Oceanic plate forms trench
Examples
Rocky mountains (N. America)
Himalaya mountains (Central Asia

19. Earthquakes
Faults – breaks in Earth’s crust where plates slide past each other
Rocks under stress break off triggering ground vibrations - called earthquakes
Magnitude (Richter Scale)
Measure of energy released
2.0 – smallest felt
9.5 – largest recorded
Increase of 1 whole number = 31.7 times more energy

20. Where Earthquakes Occur
Most occur at or near plate boundaries

21. Earthquake Hazard
Earthquake hazard level determined by past & present seismic activity
Hazards (effects) include
Ground shaking (building damage/settling of ground beneath to different level)
Ground displacement
Flooding (breakage of levies, dams, Tsunamis)
Fire (broken gas & power lines)
Human hazards due to man-made structures
Being crushed, buried or burned or drowning
National Hazards Maps used by cities, counties & local governments to update & create more stringent building codes

22. Volcanoes Mountains built from magma (molten rock)
Magma rises to surface from interior
Most common at convergent or divergent plate boundaries
Can occur on land or in oceans
Block between separating faults cracks, drops into asthenosphere forming a rift. Magma seeps upward to fill in crack

23. Volcanoes: The Ring of Fire
Majority of active volcanoes on land located along tectonic plate surrounding the Pacific Ocean
North American Plate
Eurasian Plate
South American Plate
Pacific Plate
Australian Plate
Antarctic Plate

24. Local Effects of Volcanic Eruptions
Clouds of hot ash, dust, & gases flow down the slopes of volcanoes searing anything in its path
Obscures sunlight, killing plants & animals
Volcanic ash mixes with water producing mudflows
Water contamination
Land contamination
Collapse of buildings, burying of crops, & damage to vehicle engines due to falling ash

25. Global Effects of Volcanic Eruptions
Can cause changes in Earth’s climate
Ash & sulfur-rich gases reach upper atmosphere & reduce sunlight reaching Earth’s surface
Reduction in sunlight reduces average global temperatures

26. Erosion
Process resulting in materials of the Earth’s surface being loosened, dissolved or worn away & transported from one place to another by natural agents such as wind, water, ice or gravity
Water erosion
Rivers carve deep canyons or gorges into bedrock
Depositing of dust, pebbles, rocks forms new land areas
Oceans erode coastlines
Wind erosion
Removal of most fertile part of soil lowering soil productivity
Creates sand dunes