Unit 2: The Earth System

1. Unit 2: The Earth System Atmosphere, Hydrosphere & Geosphere

3. Function, Composition and Structure of the Atmosphere

4. Functions • Air we breath, plants use in photosynthesis • Filters solar energy, blocking much of harmful UV wavelengths • Protects us from “space junk” • Allows for a natural greenhouse effect keeping earth warm enough for liquid water and life • Cycles moisture and heat throughout earth in moving air systems providing weather patterns and the water cycle • weathers and shapes earth’s surface, allowing the rock cycle

5. Composition of Today’s Atmosphere • Variable components: • Water (0-4%) • Dust, ozone, pollution

6. Compare to neighbors

7. Structure of Atmosphere • Gas molecules thin with altitude • What holds them near earth’s surface?

8. Atmosphere blends to Exosphere

11. Heating the Atmosphere • Troposphere=heated by terrestrial radiation • Stratosphere& Mesosphere=absorption and re-radiation of shortwave radiation in the ozone layer • Thermosphere=absorption and re-radiation of shortwave radiation by oxygen

12. Evolution of the Atmosphere • Loss of original atmosphere due to solar wind • Formation of early atmosphere by outgassing • Evolution of atmosphere by interactions with biosphere, hydrosphere, and geosphere • Today’s atmosphere • Human’s effect on today’s atmosphere

13. Solar wind • 1 million tons of matter out into space every second! • 95% protons or H+ ions, plasma state

14. Not as dense Plasma vs. gas Solar wind is different than earth wind

15. Solar Wind wipes early atmosphere away • When sun first began to shine, early atmosphere in inner solar system blown out past the asteroid belt where it was cooler • Only dense materials with very high melting points able to remain (rocky, metallic elements)

16. Outgassing • Gases from volcanoes • water vapor (H2O), • carbon monoxide (CO), • carbon dioxide (CO2), • hydrochloric acid (HCl), • methane (CH4), • ammonia (NH3), • nitrogen (N2), • sulfur gases. • no free oxygen • Additions to atmosphere: perhaps from comets?

17. Evidence for composition of early atmosphere • Today’s volcanic eruptions • Rocks from early earth history • Early organisms are anaerobic (cannot survive in O2)

18. Banded Iron Formation • not present in rocks younger than 1.8 - 2.5 billions of years ago, when oxygen starting becoming more abundant. • Alternating layers of magnetite, hematite (iron oxide) and silica-rich minerals • Struggle between oxygen-rich and oxygen-poor environment

19. The Oxygen explosion • The amount of oxygen increased due to early life forms, such as cyanobacteria that produce oxygen as a waste product • Water vapor split by incoming solar radiation into hydrogen and oxygen, hydrogen escapes

20. Role of the Oceans • Environment for early life • Absorption of carbon dioxide and other toxic gases

21. Consequences of Oxygen Build-up • Development of ozone (O3) layer which absorbs harmful UV radiation and eventaully allowed life on land • End of banded iron formations which only formed in low O2 • Oxygen breathing organisms evolved

22. Composition, function, structure of Hydrosphere

23. Function & Significance of Hydrosphere • Necessary for the evolution and the abundance of life • Helps circulate heat • Absorbs and facilitates the storage of carbon dioxide allowing earth to develop and maintain low CO2 levels

24. Structure and Composition • All water on earth recycles between reservoirs • Most freshwater is in the ground, some in lakes and rivers, atmosphere

25. Water Cycle

26. Water: changes of state

27. Evolution of the Hydrosphere • Outgassing (& perhaps comets) adds water vapor to atmosphere • Saturated atmosphere causes great rains • Great rains cool surface and collect in massive freshwater ocean • Landmasses weather and running water carries dissolved material (salts) to the ocean • Water cycle, driven by sun, continues to cycle water today

28. Great Rains

29. Ocean getting salty • Weathering of rocks • Undersea volcanoes and vents • Balance of salt, not getting saltier

30. Composition, Structure, & Function of Geosphere

31. Function & Significance of Geosphere • Storage of most of earth’s matter • Volcanic activity responsible for atmosphere, climate changes, new crust • Plate movements causing crust to be recycled including elements that accumulate such as carbon and “salt” • Provides varied topography on which both dry and wet land creatures dwell • Weathers to form soil from which land plants derive many nutrients

32. Evolution of Geosphere • Solid rock, metal and ice accrete to form protoplanet from solar nebula • Gravitational compression & impacts cause early earth to become molten • Differentiation based on density formed layers out of molten earth, gasses escaped. • Great collision causes large chunk of crustal rock to rip away & form moon. Gravity pulls both back into molten spheres

33. Earth’s Layered Structure

34. Evolution of Geosphere cont. 5. Crust cools but heat from within causes eruptions of rock and gas to continue, also causes plates to shift 6. Plate collisions and volcanic activity create landmasses above sea level 7. Heat within drives plate motions causing landmasses to shift and rocks to recycle 8. Interaction between weathering and uplift create today’s landscape

36. Plate Tectonics

37. Rock Cycle

38. What is the geopshere made of? • Common elements • Elements make up minerals • Rocks are made of minerals

39. 3 main types of rocks • Based on formation • Igneous= • Sedimentary= • Metamorphic= • Common characteristics of each

40. Rodinia

41. Gondwana

42. Brr…

43. Oceans begin to close

44. Pangea is forming, Appalachians

45. Greatest extinction (99%) of all time!

46. Pangea breaks up

47. Major Extinction

48. Himalayas form

49. Most recent Ice age

50. Today