Welcome to ESC 102 Evolution of Earth and Life Historical Geology Fall 2014

1. Welcome to ESC 102 Evolution of Earth and Life Historical Geology Fall 2014

3. Earth Systems • Lithosphere: Earth’s solid rocky mass • Hydrosphere: All of earth’s water • Atmosphere: The thin gaseous layer above Earth’s surface • Biosphere: All of earth’s life forms

4. Earth Systems • Text:atmosphere, biosphere, hydrosphere, lithosphere, mantle, core The solid portions are sometimes collectively referred to as “geosphere”

5. Three Themes tell the story of the evolving Earth • The Theory of Plate Tectonics Solid Earth is composed of plates that move over Earth’s surface. • The Theory of Organic Evolution Earth’s biota – all living things – has evolved or changed through history. • The Geologic Time Scale Geologic processes take place within extensive geologic time -~ 4.6 billion years of Earth’s history.

6. UniformitarianismThe physical , chemical, and biologic processes that occur today must have occurred in the past. Rock layers reveal sequences of events based on processes that occur today.

7. Geologic Time Smith’s map took many years to complete and helped establish the geologic time scale.

8. Geologic Time Geologic Periods were determined by the rock record and the fossils contained in distinct layers. (1841) Numerical dates millions of years before the present have been determined by using radioactive isotope decay. (1913)

9. 1/29 Hypothesis or Theory? • The scientific method brings an orderly and logical approach to decoding geologic evidence • A hypothesis is a tentative explanation for observations • A theory is well-tested and well-supportedby objective evidence

10. How old is the universe? • When? Scientists believe the universe was formed about 15 billion years ago • 13.7 billion years ago (text: 14by) • How? The Big Bang is a model for the “beginning” of the universe • “Show me”! What is the evidence?

11. Evidence of the Big Bang • Pervasive background radiation of 2.7o C above absolute zero is observed in space(-273o C or -460o F) “Afterglow” of the Big Bang discovered in 1965 As predicted, it was cosmic microwave radiation from space

12. Evidence of the Big Bang • Galaxies moving away – expanding universe(proposed by Hubble) Imagine the surfaceof a balloon as itis inflated. Locations on the surface move away from one another The further away objects are, the faster they are moving away = acceleration.

13. A E A C B E C B

14. Doppler effect • https://www.youtube.com/watch?v=h4OnBYrbCjY

15. Evidence of the Big Bang To determine the Age of the Universe Determine rate of expansion: look at the most distant objects“Back-model” to a time when the galaxies would be together in the same space

16. How far can we “see” into space?

17. Big Bang Model Research • A 7 year satellite observation project mapped the cosmic microwaves in space • Revealed the nature of many components that had been predicted in various models. • The WMAP project since 2002 has enabled scientists to refine the age of the universe to 13.7 billion years and the “shape” of its surfaces. • 1993Age: 12-20 Billion YearsSize: 30 Billion Light Years2006 Age: 13.7 Billion Years Size: 94 Billion Light Years

18. Big Bang model • Initial state: NO time, NO matter, NO space • Universe was pure ENERGY • During the FIRST second of time: --very dense matter came into existence --The four basic forces separated: gravity electromagnetic force strong nuclear force weak nuclear force Enormous expansion occurred

19. Big Bang Model • 300,000 earth years later: • Atoms of hydrogen and helium formed • Light (photons) burst forth for the first time • Next 200 million years: • Continued expansion • Stars and galaxies began to form • Elements heavier than hydrogen and helium began to form within stars by nuclear fusion

20. The WMAP data indicate our universe is 13.7 billion years old, and made up of only only four percent ordinary atoms. Dark matter makes up about 23 percent. The remaining 73 percent is the enigmatic "dark energy."

21. 9 billion years later….. The formation of the solar system

22. Solar Nebula Theory • cloud of gases and dustformed a rotating disk Solar nebula theory • condensed and collapsed due to gravity • forming solar nebula • with an embryonic Sun • surrounded by a rotating cloud

23. Solar Nebula Theory • Planetesimals have formed • in the inner solar system, • and large eddies of gas and dust • remain far from the protosun

24. Solar Nebula TheoryRequires Cosmic Dust Aggregation ________

25. The planets formed with distinctorbits around the sun.Some planets have satellites which orbit individual planets.

26. Solar Nebula Theory Is there Evidence? The Hubble Telescope image : solar nebula protoplanetary disk “proplyd” in Orion Nebula with dozens of others. The proto star is the bright glow; dark area is a dense molecular cloud.

27. NASA image clearly shows that this star has 4 distinct rings. These rings will eventually coalesce into solid bodies called planets. Solar Nebula Theory

28. Terrestrial Planets Mercury Venus Earth Mars Small in size Composed of rock Metallic cores Asteroid Belt Jovian Planets Jupiter Saturn Uranus Neptune Large in size. Composed of hydrogen, helium, ammonia, methane Small rocky cores Kuiper Belt Pluto: no longer has planet status The Planets

30. Earth’s Very Early History • Started out cool about 4.6 billion years ago -- with uniform composition • Heated up enough to melt iron and nickel within the newly formed Earth • Heat sources: • gravitational compression • radioactive decay • meteorite impacts

31. Earth’s Very Early History The earth and moon were heavily bombarded in Earth’s early history.

32. Earth’s Differentiation:Key event in Earth History • Differentiation = segregated into layers of differing composition and density • Early Earth was probably uniform • After heating, molten iron and nickel sank to form the core • Lighter minerals flowed up to form mantle and crust

33. Forming the Moon • Impact by Mars-sized planetesimal with early Earth 4.6 to 4.4 billion years ago Ejected a large quantity of hot material that cooled and coalesced to form the moon

34. Forming the Moon Impact hypothesis

35. Most of the lunar material came from the mantle of the colliding planetessimal Moon is smaller & cooled quickly. Heavily cratered (light areas) --massive meteorite bombardment Mare areas of lava flows more likely due to impact than tectonics

36. Earth—Dynamic Planet • Earth was also subjected • to the same meteorite barrage • that pock-marked the Moon • Why isn’t Earth’s surface also densely cratered?

37. Earth—Dynamic Planet Major elements on Earth Top 4 most abundant elements by OxygenSiliconaluminum Hydrogen

38. Earth—Dynamic Planet Earth’s Interior Layers • Compositionally:3 layersCrustMantleCore

39. Plate Tectonics Theory • Lithosphereis broken into individual pieces called plates • Plates move over the weak layer • as a result of underlying convection cells

40. Plate Tectonics Theory

41. Theory of Organic Evolution • Provides a framework for understanding the history of life • Provides the mechanism of natural selection

42. Theory of Organic Evolution • All present-day organisms are descended from organisms that lived during the past • Natural selection results in the survival to reproductive age of those best adapted to their environment

43. Theory of Organic Evolution • The fossil record: the most compelling evidence in favor of evolution Fossils demonstrate that Earth has a specific history of life Modern Chromosome Theory: fills in the blanks by studying the genetic makeup of any organism that can provide DNA

44. Geologic Time • Human perspective seconds, hours, days, years • Ancient human history hundreds or even thousands of years • Geologic history millions, hundreds of millions, billions of years

45. UniformitarianismThe Present is the key to the past THE UNIFYING PRINCIPLE OF GEOLOGY Present day mud cracks Ancient mud cracks