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23.3 – Cenozoic Era

23.3 – Cenozoic Era. Cenozoic Era. Began about 65 million years ago Present Era About 1.5% of Earth’s history Continents haven’t changed much Just a little closer to each other at the start of this Era Time of increased tectonic activity Mountain ranges formed Alps & Himalayas.

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23.3 – Cenozoic Era

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  1. 23.3 – Cenozoic Era

  2. Cenozoic Era • Began about 65 million years ago • Present Era • About 1.5% of Earth’s history • Continents haven’t changed much • Just a little closer to each other at the start of this Era • Time of increased tectonic activity • Mountain ranges formed • Alps & Himalayas

  3. Dramatic changes in climate • At times, continental ice sheets covered 1/3 of earth • Various species became extinct and others appeared • Mammals become dominant life-forms • Age of Mammals

  4. Divided into 2 periods • Tertiary • Time before last Ice Age • Quaternary • Includes present • Each period divided into Epochs

  5. Cooling • As Australia and Antarctica split, worldwide cooling began • Caused by change in ocean currents • Previously warm water flowed from Pacific, Atlantic, and Indian Oceans to moderate Antarctica’s temperature • Once split, Antarctica was isolated around South Pole • Cold current began to flow • Permanent ice cap grew during Oligocene

  6. Miocene Warming • Climate warmed up again • Ice cap began to melt • Ocean flooded North America • Trend reversed in middle of Miocene • Set stage of Ice Ages

  7. Ice Ages • Late Pliocene to Pleistocene • Ice covered much of Northern Hemisphere • Glaciers advanced and retreated at least four times • Ohio and Missouri Rivers mark southernmost point of glaciers • Glaciers carved our lakes and valleys we see today

  8. Mountain Building • Erosion wore down Rocky Mountains but uplift continued • Volcanism returned at the end of the Eocene

  9. Subduction in the West • Oceanic plate subducted under Pacific Northwest • Plate completely disappeared • Cascade Mountains uplifted • North American plate began to move against Pacific Plate • Transform Boundary that created San Andreas Fault

  10. Basin & Range Province • Created by North American moving against Pacific Plate • Southwestern part of United States • Hundreds of parallel mountains • Formed as stress in crust pulled it apart

  11. Continental Collisions • Final breakup of Pangaea • Some continents separated while others collided • Africa colliding with Eurasia built the Alps • Eliminated Tethys Ocean that once separated Eurasia and Gondwana • Remnants can be found in 4 bodies of water in Europe • India crashed into Asia to form Himalayan Mountains

  12. Tectonic Forces • Scientists think Earth is in a relatively warm phase • Future climate will become cooler • Tectonic forces continue to shape earth • In about 250 million years, tectonic forces will largely eliminate the Atlantic Ocean and once again form a supercontinent

  13. Cenozoic Life • Marine organisms survived mass extinction at the end of the Cretaceous • Populated oceans during Cenozoic Era • Forest began to dominate land • Grasses appeared as climate cooled • Diversification of many new mammals resulted

  14. Oligocene Epochs • Climate continued to get drier and cooler • Favored growth of grasses and cone-bearing and hardwood trees • Earlier types of mammals became extinct • Larger species flourished • Deer, pigs, horses, camels, cats, & dogs

  15. Ice Age • Climate began to cool and new animals evolved • Mammoth • Saber-toothed cat • Modern Humans – Homo Sapiens

  16. Baby Mammoth http://img.rian.ru/images/10412/88/104128804.jpg http://www.telegraph.co.uk/scienceandtechnology/science/sciencenews/5262616/Secrets-of-37000-year-old-baby-mammoth-revealed.html

  17. Humans • Bipedal locomotion • First bipedal humanlike primates appeared about 6 million years ago during the Late Miocene • Earliest modern humans appeared about 195,000 years ago • Migration was influenced by Ice Age • Bering Strait was exposed and Humans likely walked across to North America

  18. Pleistocene Epochs • Several periods of glaciations • Animals had special characteristics that allowed them to endure the cold • Other animals moved to warmer regions • Less-adaptable species became extinct • Fossils of early ancestors of humans appear • Hunters which led to extinction of many large mammals

  19. Holocene Epochs • Includes present • Began when last ice age ended • As ice sheets melted, seas rose and coastlines took shape • Great Lakes formed • Modern humans developed agriculture and began to make tools

  20. In-Class Assignment/Homework • 23.3 Cenozoic & Review WKT

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