23.3 – Cenozoic Era
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Transcript of 23.3 – Cenozoic Era
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
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
Divided into 2 periodsTertiary
○ Time before last Ice AgeQuaternary
○ Includes present
Each period divided into Epochs
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
Miocene Warming
Climate warmed up againIce cap began to meltOcean flooded North America
Trend reversed in middle of MioceneSet stage of Ice Ages
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
Mountain Building
Erosion wore down Rocky Mountains but uplift continued
Volcanism returned at the end of the Eocene
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
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
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
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
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
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
Ice Age
Climate began to cool and new animals evolvedMammothSaber-toothed catModern Humans – Homo Sapiens
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
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
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
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
In-Class Assignment/Homework 23.3 Cenozoic & Review WKT