1. Chapter 19 The Neogene World

2. Guiding Questions How did marine life of Neogene time differ from that of Paelogene time? What happened to grasses and grasslands early in Neogene time? Why might we label the Miocene Epoch the Age of the Apes? Why did global climates change during the Pliocene Epoch? What tectonic events elevated mountains in the American West in Neogene time?

3. 11,600 ybp 23 Million years

4. Neogene Life Marine life –Miocene ancestral whales Sperm whale Baleen whales Dolphin –Miocene recovery of planktonic foraminifera

5. Neogene Life Terrestrial Life –Grasses –Herbs and weeds –Requires arid climate Cooler climate linked to Antarctic glaciation

6. Neogene Life Isolation of Antarctica led to glaciation –Global cooling

7. Neogene Life Mammals –Groups of large mammals –Many adapted to open terrain Even-toed ungulates –Bovidae Elephants Carnivorous mammals –New world primates

8. Neogene Life Spread of C 4 grasses –C 4 plants Incorporate more carbon 13 than C 3 grasses Five times more silica –Wears down teeth of grazers

9. Neogene Life Why the spread of C 4 grasses? –Global climate change Aridity, not CO 2, drop Alkenones indicate CO 2 rise

10. The Ice Age Glacial Maximum –Extent of continental glaciation Six lines of evidence Erratic boulders

11. The Ice Age Glacial till and basins associated with glaciation Depression of the land –Hudson Bay

12. The Ice Age Glacial scouring –Lower parts of mountains of northeast U.S. are smooth –Tops were not scraped by ice sheets

13. The Ice Age Lowering of sea level –Exposed continental shelves

14. The Ice Age Migration of species –Mammals crossed Bering Strait on land corridors –Vegetation changed in response to global changes

15. The Ice Age Pollen –Reconstruct vegetation changes –European changes

16. The Ice Age Chronology of glaciation Oxygen isotope ratios of foraminiferan skeletons in sediments –Oceans are enriched in 18 O during glaciations Northern Hemisphere glaciation began ~3M years ago –Full Ice Age 2.5 M years ago

17. The Ice Age Ocean circulation changed during glaciation –Glacier in NJ –Tundra in Washington, D.C.

18. The Ice Age Great lakes –Last glacial maximum 35,000-10,000 years ago Wisconsin Stage –Remained when ice sheets melted back

19. The Ice Age Climate impacts were felt globally –Steepened temperature gradients –Increased aridity –Exception: Great Basin Unusual Lakes Great Salt Lake

20. The Ice Age Climate impacts were felt globally –Sahara expanded –Rain forests restricted Isolated gorilla species

21. The Ice Age Why did the glaciation start? Isthmus of Panama –Emplaced 3.5–3 M years ago –Started modern circulation Gulf stream carries salty Atlantic north Cools, sinks –Oceanic conveyor belt High latitudes cool

22. The Ice Age Obliquity cycles –Changes in Earth’s orbit are linked to glacial oscillations –41,000-year period initially When tilt cycle is farthest from vertical, high latitudes are coolest –Period changed to 100,000 years as glacial oscillation became less frequent –Precession Cycle: 20,000- year period

23. Regional Events-Western Uplift and igneous activity formed western provinces –Rockies –Block-fault valleys Basin and Range –Columbia River Plateau and Snake River Plain

24. Regional Events-Western Rocky Mountains –Colorado Plateau 1 mile above sea level –Folded sediments Block faulted

25. Regional Events-Western Basin and Range –North and south trending block-fault valleys Crustal thinning

26. Regional Events-Western Cascade volcanic belt –Sierra Nevada

27. Regional Events–Western Great Valley –Mesozoic sediments –From eroded Sierra Nevada plutons –Later block faulted Sierra Nevada mountains formed

28. Regional Events–Western California Coastal Range –Accreted terranes –Divided by faults San Andreas

29. Regional Events–Western Miocene –Subduction in north –Faulting and mountain building in south –Columbia Plateau basalts Up to 5 km thick –Rockies uplift Early Miocene

30. Regional Events–Western Pliocene –Igneous arc –Snake River Plain –Faulting and deformation in California –Great Basin Terrestrial

31. Regional Events–Western Why the uplift? –San Andreas transform fault –Crustal shearing led to extensional faulting Does not explain Neogene elevation of Basin and Range

32. Regional Events–Western Scablands –Bare rock scoured by floods –Water-carved channels –20,000–11,000 years ago –Bretz, 1923

33. Regional Events-Western Scablands –Depositional features –Giant ripples 5 m tall 100 m apart Water source –Lake Missoula

34. Regional Events-Eastern Tectonic movement –Salisbury embayment Downwarp of continental margin

35. Regional Events-Eastern Uplift in Cenozoic Era followed by erosion –Resistant folded rock exposed –Rivers cut through ridges

36. Regional Events–Caribbean Caribbean plate isolated

37. North American Mammal Exchange Isthmus of Panama –North and South American mammals developed separately –Pliocene uplift of isthmus allowed for exchange of terrestrial fauna

38. Himalayan Mountains Broad Tibetan plateau –3 miles above sea level

39. Himalayan Mountains Indian craton collided with Eurasia

40. Himalayan Mountains Miocene clastic sediments overlying Eocene limestone Most uplift during last 15 million years

41. Himalayan Mountains Indian plate subducted Continental collision –Fold and thrust belt –Modern motion along main boundary fault

42. Human Evolution Miocene apes radiated in Africa and Eurasia –Most were arboreal Earliest apes –6-7 M year old fossil skull Sahelanthropus Resembles both apes and humans

43. Human Evolution

44. Australopithecines –Intermediate between humans and apes –Only slightly larger brain than chimp –Broad pelvis

45. Human Evolution Tracks indicate bipedal walking Footprints similar to modern humans

46. Human Evolution Adapted to climbing trees –Long curved toes and fingers

47. Human Evolution Homo –2.4 M years ago –Larger skull –Similar thigh and pelvis bones

48. Human Evolution Stone tools –Oldowan culture Found at Olduvai Gorge

49. Human Evolution Stone tools –Acheulian Found in China in association with “Java Man”

50. Human Evolution Homo erectus –1.6 million year old boy skeleton –Africa Very similar to modern humans

51. Human Evolution Neanderthals –Homo heidelbergensis Heidelberg, Germany 200,000–700,000 years old –Homo antecessor

52. Human Evolution Stone tools –Neanderthals Mousterian More sophisticated than Homo erectus tools

53. Human Evolution Neanderthal burial sites –Possible religion

54. Human Evolution Cro-Magnon culture –European –Cave paintings of France and Spain