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23.3 – Cenozoic Era

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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. - PowerPoint PPT Presentation

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Cenozoic Era Began about 65 million years ago

Present EraAbout 1.5% of Earth’s history

Continents haven’t changed muchJust a little closer to each other at the start

of this Era Time of increased tectonic activity

Mountain ranges formedAlps & Himalayas

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Dramatic changes in climate At times, continental ice sheets covered

1/3 of earthVarious species became extinct and others

appeared

Mammals become dominant life-formsAge of Mammals

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Divided into 2 periodsTertiary

○ Time before last Ice AgeQuaternary

○ Includes present

Each period divided into Epochs

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Cooling As Australia and Antarctica split, worldwide

cooling beganCaused by change in ocean currentsPreviously warm water flowed from Pacific,

Atlantic, and Indian Oceans to moderate Antarctica’s temperature

Once split, Antarctica was isolated around South PoleCold current began to flowPermanent ice cap grew during Oligocene

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Miocene Warming

Climate warmed up againIce cap began to meltOcean flooded North America

Trend reversed in middle of MioceneSet stage of Ice Ages

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Ice Ages

Late Pliocene to Pleistocene Ice covered much of Northern

Hemisphere Glaciers advanced and retreated at least

four timesOhio and Missouri Rivers mark

southernmost point of glaciersGlaciers carved our lakes and valleys we

see today

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Mountain Building

Erosion wore down Rocky Mountains but uplift continued

Volcanism returned at the end of the Eocene

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Subduction in the West Oceanic plate subducted under Pacific

NorthwestPlate completely disappearedCascade Mountains uplifted

North American plate began to move against Pacific PlateTransform Boundary that created San Andreas

Fault

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Basin & Range Province

Created by North American moving against Pacific PlateSouthwestern part of United StatesHundreds of parallel mountains

Formed as stress in crust pulled it apart

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Continental Collisions Final breakup of Pangaea Some continents separated while others

collidedAfrica 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

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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

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Cenozoic Life

Marine organisms survived mass extinction at the end of the CretaceousPopulated oceans during Cenozoic Era

Forest began to dominate land Grasses appeared as climate cooled

Diversification of many new mammals resulted

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Oligocene Epochs

Climate continued to get drier and coolerFavored growth of grasses and cone-

bearing and hardwood trees

Earlier types of mammals became extinct

Larger species flourishedDeer, pigs, horses, camels, cats, & dogs

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Ice Age

Climate began to cool and new animals evolvedMammothSaber-toothed catModern Humans – Homo Sapiens

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Baby Mammoth

http://www.telegraph.co.uk/scienceandtechnology/science/sciencenews/5262616/Secrets-of-37000-year-old-baby-mammoth-revealed.html

http://img.rian.ru/images/10412/88/104128804.jpg

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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 AgeBering Strait was exposed and Humans

likely walked across to North America

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Pleistocene Epochs

Several periods of glaciationsAnimals had special characteristics that

allowed them to endure the coldOther animals moved to warmer regionsLess-adaptable species became extinct

Fossils of early ancestors of humans appearHunters which led to extinction of many

large mammals

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Holocene Epochs

Includes presentBegan when last ice age endedAs ice sheets melted, seas rose and

coastlines took shape

Great Lakes formed Modern humans developed agriculture

and began to make tools

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In-Class Assignment/Homework 23.3 Cenozoic & Review WKT