1. The Dynamic Earth
Unit 3

2. 3-1 The Earth as a System
The Earth is an integrated system that consists of rock, air, water, and living things that all interact with each other.
Scientists divided this system into four parts:
-The Geosphere (rock)
-The Atmosphere (air)
-The Hydrosphere (water)
-The Biosphere (living things)

3. The Earth as a System

4. The Geosphere -Extends from the core to the crust.
-Mostly solid, rocky part of the Earth.
-Extends from the core to the crust.
-The atmosphere is a mixture of gases that makes up the air
we breathe.
-Gases are found in the first 30 km above the Earth’s surface.

5. The Hydrosphere
-Made up of all the water on or near the Earth’s surface.
-Oceans cover nearly three- quarters of the globe.
-Water is also found in the atmosphere, on land, and in the soil.

6. The Biosphere -Part of the Earth where life exists.
-Thin layer that extends from about 9 km above the Earth’s surface to the bottom of the ocean.
-Made up of parts of the
geosphere, atmosphere,
and hydrosphere

7. Discovering Earth’s Interior
-Seismic waves are used to learn about Earth’s interior.
-Seismic waves travel through Earth’s interior during an earthquake.
-The speed and direction of seismic waves reveal the different layers of the Earth.

9. The Composition of the Earth
-The Earth is divided into three layers:
The crust
The mantle
The core
-These layers are made up of
progressively denser material
toward the center of the Earth.

10. The Crust -Makes up less than 1 percent of the planet’s mass.
-Thin, solid outermost layer of the Earth.
-Makes up less than 1 percent of the planet’s mass.
-Is 5 km to 8 km thick beneath the oceans and km thick beneath the continents.

11. The Mantle Layer of molten rock between the Earth’s crust and core.
-Makes up 64 percent of the mass of the Earth.

12. The Core
-Central part of the Earth below the mantle. -Composed of nickel and iron. -Estimated temperature: btw 4,000°C to 5,000°C - it is solid because of enormous pressure.

13. Earth’s Structure
Earth can be divided into five layers based on physical properties: -Lithosphere: solid, outer layer of the crust and rigid upper part of the mantle. -Is divided into huge pieces called tectonic plates.

14. Earth’s Structure (cont’d)
-Asthenosphere: solid, plastic layer of the mantle beneath the lithosphere. -Made of slowly flowing mantle rock, which allows tectonic plates to move on top of it. -Mesosphere: lower part of the mantle

16. Plate Tectonics Divisions of lithosphere.
Glide across the asthenosphere.
Major plates: Pacific, North America, South America, Africa, Eurasian and Antarctic.

17. Plate Boundaries Site of major geologic activity.
Plates may collide, pull apart, or “slip” past one another.
Forces may result in earthquakes, volcanoes or mountain building.

18. Earthquakes Faults are breaks in the crust.
Slippage along faults vibrate crust create earthquakes.
Richter scale quantifies magnitude earthquake energy.
-smallest magnitude: 2.0
-largest magnitude: 9.5
Most active fault in N.A.: San Andreas along California.

19. Where do Earthquakes Occur?

20. FYI: Earthquake Hazard
Scientists cannot predicts when earthquakes will take place. However, they can help provide information about where earthquakes are likely to occur helping people prepare.
An area’s earthquake-hazard level is determined by past and present seismic activity.
Earthquake-resistant buildings, built in high risk areas, are slightly flexible so that they can sway with the ground motion preventing them from collapsing.

21. Plate Tectonics and Mountain Building
-Colliding plates form mountain ranges
Ex. The Himalaya Mountains

22. Volcanoes
Mountain built from magma. Can occur on land or in the sea. Often located near tectonic plate boundaries- plates are either colliding or separating from one another. Majority of active volcanoes on land are located along tectonic plate surrounding the Pacific Ocean.

23. Volcanoes: The Ring of Fire

24. Local Effects of Volcanic Eruptions
-Clouds of ash, dust, and gases can flow down the slope of a volcano at speeds of up to 200 km/hr.
-Can burn everything in its path.
-Volcanic ash mixed with water can produce mudflows.
-Falling ash can cause buildings to collapse under its weight, bury crops, damage the engines of vehicles, and cause breathing difficulties.

25. Global Effects of Volcanic Eruptions
-Major eruptions can change Earth’s climate for several years.
-Clouds of volcanic ash and sulfur rich gases may reduce the amount of sunlight that reaches the Earth’s surface.
-Reduction in sunlight can cause a drop in the average global surface temperature.

26. Erosion
-Process in Earth’s surface is loosened, dissolved, or worn away and transported by wind, water, ice or gravity.
-Wears down rocks and makes them smoother with time (reason why older mountains are smoother than younger ones).

27. Water Erosion -Waves from ocean storms can erode coastlines.
-Rivers and oceans can produce major changes on Earth’s surface.
-Waves from ocean storms can erode coastlines.
-Rivers can carve deep gorges into the landscape.

28. Wind Erosion
-At beaches and in deserts, wind can blow soil away quickly.
-Soft rocks, such as sandstone, erode more easily than hard rocks, such as granite do.

29. Sect 2: The Atmosphere Mixture of gases: Nitrogen (N₂)- 78%
Oxygen (O₂) %
CO₂, H₂O, argon- 1%
Insulates the earth from heat and cold.
Held in place by gravity

30. Layers of the Atmosphere
Troposphere: closest to surface, site of weather.
Stratosphere: above the troposphere, site of ozone
-ozone (O₃) protects against
harmful UV radiation from
sun.
Mesosphere: coldest layer.
Thermosphere: lowest layer is
ionosphere- site of aurora borealis

31. Energy in The Atmosphere
Energy from the sun is transferred as heat by:
Radiation: across space.
Conduction: warm to cold.
Convection: air molecules
-hot air rises, cold air sinks.

32. The Greenhouse Effect
Process in which gases trap heat near the Earth’s surface.
-sunlight heats the surface
the day.
-some of the heat escapes back
into space.
-remainder of heat is trapped by
greenhouse gases (methane, CO₂,
nitrous oxide, water vapor).

33. Sect 3: The Hydrosphere and Biosphere
Hydrosphere: includes all water
on or near Earth’s surface…
-oceans, lakes, icecaps, soil, clouds.

34. The Water Cycle Continuous movement of water between air and land.
3 major processes:
-evaporation: liquid to vapor.
-condensation: vapor to drop-
lets, forms clouds.
-precipitation: rain, snow, sleet,
hail.

35. Oceans Single, interconnected body of water. Covers 70% of planet.
Largest ocean: Pacific
-deepest point: Challenger Deep
-currents move clockwise north of
equator; counterclockwise south
of the equator.

36. Oceans (cont’d) 2nd largest ocean: Atlantic Smallest ocean: Arctic
-unique feature: pack ice covers
much of ocean’s surface.

37. Ocean Water Contains dissolved salts, most
of which is sodium chloride.
Salinity: concentration of all salts in water.
-lower where fresh water flows
into ocean.
-higher where water evaporates
quickly.

38. Ocean Zones
Surface zone: warm top layer; currents mix warm and cool water.
Thermocline: boundary between warm and cold water;
temperature drops faster with
depth than other zones.
Deep zone: bottom zone with coldest temperatures.

39. Ocean Currents Surface: wind driven, result from global winds.
-may be warm or cold.
-can flow for hundreds of km.s
ex. Gulfstream
-influence climate of land.
Deep: flow slowly on ocean floor.
-cold polar water sinks, moves
toward the equator.

40. Global Temperature Regulator
Ocean waters absorb, store energy from sunlight.
Water absorbs, releases heat more slowly than land, results in slower atmospheric temperature changes.
Temperature regulation prevents
extremes on Earth.

41. Fresh Water Contains insignificant amounts of salts.
≈ 3% of all water.
Most is locked up in icecaps, glaciers
Liquid form is found in lakes, rivers, wetlands, the soil, atmosphere.

42. River Systems Network of streams that drains an area of land.
Contains all of the land drained by a river, including the main river and its tributaries: small streams that empty into a river.
Mississippi River system covers ≈
40% of the contiguous U.S.

43. Groundwater Area underground that collects rain, melting snow.
Less than 1% of all water.
Fulfills the human need for fresh drinking water, supplies agricultural and industrial needs.
Aquifers: rock layer that stores and allows the for the flow of groundwater.
-recharge zone: surface of land
where water enters aquifer.

44. The Biosphere
Narrow layer of planet where life is found (includes geosphere, lower atmosphere, hydrosphere).
Closest to surface because of ample sunlight there.
Dependent on gravity, water, nutrients.

45. Energy Flow Through the Biosphere
Begins as sunlight trapped by plants in photosynthesis.
Dead organisms are broken down, its energy and nutrients are passed on to others.
Recycling of nutrients and energy flow make life possible.

46. Mount St. Helens, Washington State

47. Mount St. Helens, Washington State