2. Outline Stratigraphy: –Study of the layers of sedimentary rocks Unconformities Correlation Relative dating Absolute dating

3. Optional Field Trip Exercise Changed from March 18 to March 4 Due March 9 at 1:10 pm Zuhl Museum Alumni Center, 775 College Av.

4. Sedimentation in lake or sea

5. Sedimentation in lake or sea Sediments are deposited in horizontal layers and slowly change into rock.

6. Principle of Original Horizontality In stratigraphy: Sedimentary layers are originally deposited as horizontal sheets. Folded or tilted beds indicates something happened to them later

7. TIME 1 Beneath the sea, sediments accumulated in beds. B C D A

8. Principle of Superposition In stratigraphy: Sedimentary layers at the bottom of a sequence are OLDER than the ones on top If older beds are on top, then the sequence has been turned upside down

9. Younger Older

10. Unconformities: Missing time

12. Tapeats Sandstone (500 million years) Cardenas Basalt (1.1 billion years)

13. Angular Unconformity

14. Nonconformity: seds over granite

16. Nonconformity

19. Sequence of events: 1)Deposition of sediment 2)Tilting of beds 3)Erosion 4)Deposition of sediment

20. Write down the sequence of events for this location. 1.Deposition of sediment

21. 2.Folding 3.Erosion 4.Deposition of sediment on top

22. TIME 1 Beneath the sea, sediments accumulated in beds. B C D A

23. TIME 2 Tectonic forces caused uplift, exposing the beds to erosion. B C D A Uplift

24. TIME 3 Erosion stripped away bed D and part of C. B C A

25. TIME 4 Subsidence allowed a new layer, E, to be deposited. B C A E Subsidence Unconformity

26. TIME 1 Beneath the sea, sediments accumulated in beds.

27. TIME 2 Tectonic forces caused uplift, folding, and deformation. Uplift Compression

28. TIME 3 Erosion stripped away the tops of the folded layers, leaving portions of several layers exposed.

29. TIME 4 Subsidence allowed new sediments to be deposited. Subsidence Angular unconformity

31. Plants grow on this surface

32. 10 cm

33. Principle of Faunal Succession In stratigraphy: Fossils appear in a definite sequence This sequence can be used to CORRELATE beds in one area to another

36. Outcrop AOutcrop B I II III

37. Outcrop AOutcrop B I II III

38. Outcrop AOutcrop B I II III

39. Outcrop AOutcrop B I II III Some of the fossils found in outcrop A are the same as fossils found in outcrop B, some distance away.

40. Outcrop AOutcrop B I II III Some of the fossils found in outcrop A are the same as fossils found in outcrop B, some distance away. Layers with the same fossils are the same age.

41. Outcrop AOutcrop B I II III Some of the fossils found in outcrop A are the same as fossils found in outcrop B, some distance away. Layers with the same fossils are the same age.

42. Stratigraphic succession A composite of the two outcrops. Younger rocks Older rocks I II III

45. The Age of the Earth 4,560,000,000 years or 4.6 billion years

46. Geologic Time Scale Precambrian (4.6 Ga to 540 Ma) Paleozoic (540 Ma to 250 Ma) Mesozoic (250-65 Ma) –Triassic –Jurassic –Cretaceous Cenozoic (65 Ma to the present)

47. LIFE ON EARTH 3.5 billion year old bacteria and algae

48. Cambrian explosion of life: 540 million years ago

49. Trilobites-Paleozoic arthropods Today: 80% of species are arthropods

50. another Trilobite

51. Crinoids

52. First land animals: 365 Ma

53. Dimetrodon-Permian reptile

54. End of the Paleozoic Major extinction event: 96% of marine life was killed 70% land vertebrates killed

55. End of the Paleozoic

56. Mesozoic-Ammonites

58. Mesozoic-Triceratops

59. Cretaceous- Tyrannosaurus Rex

60. End of the Mesozoic Major extinction event: 85% of all species died.

62. Cenozoic-Mammoth

63. Cenozoic-Sabre tooth tiger

64. Summary Principle of superposition Principle of original horizontality Principle of faunal succession Unconformities Time scale Evolution of life