When you started second grade When you were born When you started kindergarten When you learned to ride a bike When you learned to walk When you learned to read When you lost your first tooth ID: 790175
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Slide1
Geologic Time
Slide2Events in Your Life
___When you started second grade
___When you were born
___ When you started kindergarten___When you learned to ride a bike.___ When you learned to walk.___ When you learned to read.___ When you lost your first tooth.___ Today’s date.
Construct a timeline of the important events in your life. Be sure to include all of the events listed below and any other events you feel are important. Your timeline should be constructed TWO ways:
Numerical Order (use actual dates)
Sequential Order (most recent at top)
Slide3Geologic Time Scale
Division of geologic time is based on an analysis of Earth’s rocks.
Time units were determined by the age of fossils found in the rock layer.
The scale that is created is called the Geologic Time Scale, it is a record of Earth’s history from its origin 4.6 billion years ago till today.
Slide4Slide5Geologic Time Division Sequence
Slide6Geologic Time Divisions
Eon is the longest time unit and is measured in billions of years.
Examples: The Archean Eon, the Proterozoic Eon, and the Phanerozoic Eon
The Phanerozoic Eon is the time unit we are currently in and it began 540 million years ago.
Slide7Geologic Time Divisions
Era is the next longest span of time and is measured in hundreds of millions to billions of years.
Era is defined by the differences in life forms found in the rock layers and is named based on the relative age of the fossils.
Examples: Paleozoic Era, Mesozoic Era, Cenozoic Era.
Slide8Eras
are subdivided into
periods
...periods are subdivided into epochsPeriods + Epochs = Era
Slide9Meanings:
Zoic
- “of life”
Paleo- “old”Meso- “middle”Ceno- “recent”
Slide10FOUR Eras…
PRE-CAMBRIAN –
88% of earth’s history
Paleozoic (ancient life)544 million years ago…lasted 300 million yrsMesozoic (middle life)245 million years ago…lasted 180 million yrsCenozoic (recent life)
65 million years ago…continues through present day
Slide11Precambrian Era
Atmosphere: Hydrogen and Helium probably dominant Earth’s atmosphere.
No oxygen in the atmosphere!!!!
Plate Tectonics: Numerous volcanic eruptions released large amounts of gases into the atmosphere
Slide12Precambrian Era
Age:
Geologist used radiometric dating to show the Earth is at least 4.2 billion years olds
Formations:Banded Iron Formations- alternating beds of chert and iron oxides are now mined for iron.Red Beds- sedimentary rocks that are younger than 1.8 million years are rusty red in color, which shows that Earth’s was once without oxygen.
Slide13Precambrian Era
Life:
3.5 billion years ago the emergence of cyanobacteria began to release oxygen in the Cambrian atmosphere.
Nearly all Oxygen is a result of photosynthesis.Ediacara Fauna- contained a wide variety of organisms.
Slide14Paleozoic Era
Plate Tectonics:
The ancient North American continent, Laurentia, split off from Rodinia, supercontinent, and was located near the equator.
Almost completely covered by shallow, tropical ocean.At the end of the Era, Pangaea formed when Laurasia( North America + Europe) collided with Gondwana (South America, Africa, India, Australia, and Antarctica)
Slide15Paleozoic Era
Life:
Trilobites, Extinct before the dinosaurs
came into existence, Cambrian Period is know as the “Age of the Trilobites” Articulate brachiopods were common.Seas were dominated by corals, bryozoans, brachiopods.Fish were dominant predatorFerns covered the landscape during the Devonian.Amniotes egg evolved and allowed reptiles to colonize dry land.
Slide16Early Fish
Early fish did not have jaws.
Some species of sharks were in existence at this time.
Slide17Early Land Plants
Cone bearing plants
Ferns
Mosses
Slide18Paleozoic Era
Two major mass extinctions:
Ordovician Period- 75% of all marine genera became extinct,
Caused by an episode of global cooling, glaciations.Permian Mass Extinction- larges mass extinction in the history of life.Permo-Triasic Extinction Event -95% of all species including trilobites were impacted.Possible reasonLowering of sea levels when the continents were rejoined as Pangaea (convergent boundary)Increased volcanic activity (ash and dust)Climate changes – cooler climate
Slide19Mesozoic Era
Plate Tectonics:
Pangaea broke apart
Life:Modern marine fauna present. Ex. Crabs, lobsters, shrimps, sponges, modern corals, snails, bony fish, sharks, aquatic reptiles, and aquatic mammals.Dinosaurs dominated the land.Gymnosperms or plants that produce seeds, but no flowers. Pine TreesFlowering plants appeared during the END of this era.
Slide20Slide21Dinosaurs
Slide22Mesozoic Mammals
Slide23Mesozoic Era
This era ended with a mass extinction event about 65 million years ago.
Many groups of animals, including the dinosaurs disappeared suddenly at this time.
Many scientists believe that this event was caused by a comet or asteroid colliding with the Earth.
Slide24Mesozoic Era – Mass Extinction Event
Asteroid or Comet collides with Earth.
Huge cloud of smoke and dust fills the air
Blocks out sunlightPlants dieAnimals that eat plants dieAnimals that eat plant-eaters die.However, not all forms of life died during this event. Many animals that you see today are descendants from the survivors of this extinction event.
Slide25Slide26Slide27Slide28Cenozoic Era
Age:
Began about 65 million years ago and
continues today!!!!!Climate was warm and mild.Marine animals such as whales and dolphins evolved.Plate Tectonics:Many mountain ranges formed during the Cenozoic EraAlps in Europe and Himalayas in India; Rocky Mountains in the USAGlaciers extended as far south as Ohio and Missouri Rivers.
Life:
This era is sometimes called the “Age of Mammals
”
Large mammals and Primates, dogs, cats, etc.
Homo Sapiens-
Humans
Slide29Cenozoic Mammals
Slide30Flowering Plants were common during the Cenozoic Era
Slide31Geologic Time Divisions
Periods are defined by the life-forms that were abundant or became extinct during the time in which specific rocks were deposited.
Usually measured in tens of millions of years to hundred of million of years.
They are named for the geographic region were the rocks were first observed.Example: Mississippian Period and Jurassic Period
Slide32Geologic Time Divisions
Epochs are the smallest unit of geologic time and are usually measured in millions of years to tens of millions of years.
Epoch’s are based off specific groups of organisms that have been distinguished.
Example: Oligocene Epoch is based off the marine fossils, and the Eocene Epoch is based on terrestrial plants
Slide33Video
Life after Dinosaurs:
https://www.youtube.com/watch?v=b7QSwAhMuUY