History of Geologic Thought

1. Historical Geology – Principles History ofGeologic Thought

2. Historical Geology – Principles History of Geologic Thought Myths and Legends to explain the “unknown” Creation: every society has a creation myth. Geologic processes: earthquakes, volcanoes,

3. Historical Geology – Principles History of Geologic Thought Myths and Legends to explain the “unknown” Fossils: what are they? • really organic remains? • how - when did they get there? • before/after rock formed?

4. Historical Geology – Principles History of Geologic Thought Myths and Legends to explain the “unknown” Fossils: what are they? • animals crawled into cracks • remains of a lost race • grew from seeds, solution or vapors • "figure stones" by "plastic forces"

5. Historical Geology – Principles History of Geologic Thought Myths and Legends to explain the “unknown” Fossils: what are they? • animals crawled into cracks • remains of a lost race • grew from seeds, solution or vapors • "figure stones" by "plastic forces" Fossil Folklore @ Natural History Museum, London

6. Historical Geology – Principles History of Geologic Thought Myths and Legends to explain the “unknown” Fossils: what are they? • Organisms caught in the Biblical deluge • dominated scientific thought up to mid-19th Century

7. Historical Geology – Principles History of Geologic Thought Scientific Observation: Leonardo da Vinci: 1500's Recognized that fossil shells represent ancient marine life, even though they were miles from the nearest shore. http://www.ucmp.berkeley.edu/history/images/vinci.gif

8. Historical Geology – Principles History of Geologic Thought Scientific Observation: Rationale • too fragile to be transported for miles • fossil communities,not jumbled • distinct fossiliferous layers, multiple events http://www.ucmp.berkeley.edu/history/images/vinci.gif da Vinci Geologist @ UCMP

9. Historical Geology – Principles Fundamental Stratigraphic Principles Nicolas Steno: • 1600’s • Physician - "amateur scientist" • Observed sediment and water sorting, and stratification Steno as Geologist - Theologian

10. Historical Geology – Principles Fundamental Stratigraphic Principles 1. Superposition: in a sequence of undisturbed strata, oldest layers are on the bottom, youngest on top.

11. Historical Geology – Principles 1. Superposition:

12. Historical Geology – Principles Fundamental Stratigraphic Principles 2. Original horizontality: Particles settle from a fluid under the influence of gravity http://www.jhu.edu/~eps/faculty/marsh/Riley's%20website/MMCM05-02A.jpg

13. Historical Geology – Principles Fundamental Stratigraphic Principles 2. Original horizontality: Layers must therefore be parallel and horizontal to the surface on which particles settle.

14. Historical Geology – Principles Fundamental Stratigraphic Principles 2. Original horizontality: Layers must therefore be parallel and horizontal to the surface on which particles settle.

15. Historical Geology – Principles Fundamental Stratigraphic Principles 2. Original horizontality: Layers must therefore be parallel and horizontal to the surface on which particles settle.

16. Historical Geology – Principles Fundamental Stratigraphic Principles 2. Original horizontality: Layers must therefore be parallel and horizontal to the surface on which particles settle.

17. Historical Geology – Principles Fundamental Stratigraphic Principles 2. Original horizontality: uplifted, but undisturbed beds Grand Canyon

19. Historical Geology – Principles Fundamental Stratigraphic Principles 2. Original horizontality: some tectonic event tilted these beds old on the bottom?

20. Historical Geology – Principles Fundamental Stratigraphic Principles 2. Original horizontality: some tectonic event tilted these beds old on the bottom? Maybe

21. Historical Geology – Principles Fundamental Stratigraphic Principles 3. Original lateral continuity: Strata originally extend in all directions until they: • thin to zero at edge of basin • end abruptly against some barrier

22. Historical Geology – Principles Fundamental Stratigraphic Principles 3. Original lateral continuity: Strata originally extend in all directions until they: • change gradationally into some different kind of sediment.

23. Historical Geology – Principles Fundamental Stratigraphic Principles 3. Original lateral continuity:

25. Historical Geology – Principles “Old” View of the World Catastrophism: The belief that geologic features can be explained by catastrophic events (floods) on a scale not seen today.

26. Historical Geology – Principles “Old” View of the World Catastrophism: The belief that geologic features can be explained by catastrophic events (floods) on a scale not seen today. Especially the Noachian, Biblical Flood

27. Historical Geology – Principles “Old” View of the World Catastrophism: Indirectly linked to interpretation of a young Earth. < 10,000 years old

28. Historical Geology – Principles “New” View of the World 4. Uniformitarianism: Uni - form - i - tarian - ism

29. Historical Geology – Principles “New” View of the World 4. Uniformitarianism: Uni - form - i - tarian - ism James Hutton: "The past history of our globe can be explained by what can be seen to happen now" Hutton Bio @

30. Historical Geology – Principles “New” View of the World 4. Uniformitarianism: Uni - form - i - tarian - ism "The present is key to the past"

32. http://www.bedford.k12.ny.us/flhs/science/geoscience/images/ripplemarks.jpghttp://www.bedford.k12.ny.us/flhs/science/geoscience/images/ripplemarks.jpg Present Day Beach with forming Ripple Marks

33. http://www.bedford.k12.ny.us/flhs/science/geoscience/images/ripplemarks.jpghttp://www.bedford.k12.ny.us/flhs/science/geoscience/images/ripplemarks.jpg Uniformitarianism

34. Hawaiian Volcano Lava Beds National Park New Mexico 500,000 yrs old

35. Historical Geology – Principles “New” View of the World Strict uniformitarianism: what we see today ... is exactly the conditions of the past

36. Historical Geology – Principles “New” View of the World Actualism: "Laws of nature" are inviolable: gravity, properties of water, chemical reactions 20th C

37. Historical Geology – Principles “New” View of the World Actualism: But, we now recognize that intensity and rates may vary: • climate change • tectonic spreading rates • intensity of volcanism

38. Historical Geology – Principles “New” View of the World Actualism: • the stray meteor

39. Historical Geology – Principles “New” View of the World With Actualism: We can account for events that have not occurred over the course of human time span.

40. Historical Geology – Principles Deep Geologic Time Hutton: Siccar Point Scotland Recognized significance of an unconformities.

41. Historical Geology – Principles Deep Geologic Time Hutton: Siccar Point Scotland Recognized the significance of unconformities.

42. Historical Geology – Principles Deep Geologic Time Hutton: Siccar Point Scotland

43. Historical Geology – Principles Deep Geologic Time Hutton: Siccar Point Scotland

44. Historical Geology – Principles Deep Geologic Time Hutton: Siccar Point Scotland

45. Historical Geology – Principles Deep Geologic Time Hutton: Siccar Point Scotland

46. Historical Geology – Principles Deep Geologic Time Hutton: Siccar Point Scotland

47. Historical Geology – Principles Deep Geologic Time Hutton: • developed a cyclic view of the earth • earth in a continuous state of flux old rocks decay, new rocks form (dynamic)

48. Historical Geology – Principles Deep Geologic Time Hutton: • Did not see the need to invoke catastrophes to explain geologic formations.

49. Historical Geology – Principles Deep Geologic Time Hutton: • Did not see the need to invoke catastrophes to explain geologic formations. • Observable processes and ... Time

50. Historical Geology – Principles Deep Geologic Time