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Geologic History

Geologic History. Topic: Geologic Time. Objectives: Day 1 of 3 I will know the major geologic events that have transformed our earth I will know the geologic time scale and it’s major divisions. Quickwrite:. In 2-3 sentences answer one of the questions below:

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Geologic History

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  1. Geologic History

  2. Topic: Geologic Time Objectives: Day 1 of 3 • I will know the major geologic events that have transformed our earth • I will know the geologic time scale and it’s major divisions

  3. Quickwrite: In 2-3 sentences answer one of the questions below: • What do you think a mass extinction is??? • If you know what a mass extinction is, what do you think causes them???? • Considering the age of the earth 4.6 BYO, When do you think life first appeared??

  4. Geologic Time Scale • The geological time scale is the geologic history of the planet from formation to the present. • It is starts with large divisions of time called eons and is subdivided into successively smaller units such ass eras and period • The geologic time scale is based on dominant lifeforms, and mass extinction events

  5. Geologic Time Scale Some of the major time eras include the: • Precambrian Oceans and atmosphere form • Paleozoic Invertebrates, plants and fish are the dominant forms of life • Mesozoic Reptiles are the dominant forms of life • Cenozoic Mammals are the dominant forms of life “Age of Water and Atmosphere” Precambrain “Age of Plants, fish, and invertebrates” Paleozoic “Age of Reptiles” Mesozoic “Age of Mammals” Cenozoic

  6. What is the Geologic Time Scale? Answer Bank Extinction 90% Meteorites Explosion Fossil Oxygen Humans Photosynthesis • Time scale from the beginning of earth to present • It is broken into time divisions such as Eras, & Periods that are based on the ____record, dominant life forms, and mass ____events

  7. Welcome to Earth 4.6 Billion Years ago 4.6 billion years ago Earth Forms Steam cooled and condensed into clouds, These clouds Released precipitation (rain) for millions of years, eventually forming our oceans This was what our planet was like for 4 billion years--90% of earth’s History Scientists call this period the Precambrian Our oceans slowly formed over millions of years As volcanoes released steam One of these gases was steam or (H2O) During the Precambrian, our oceans and atmosphere formed along with other important events It was a harsh environment. Meteorites bombarded our earth And volcanoes spewed out gases Precambrian CO2 CO2 CO2 H2O H2O H2O N2

  8. 4.6 billion years ago Earth Forms Remember the recipe for Photosynthesis is: CO2 + H2O  O2 + C6H12O6 Another gas given off by volcanoes is Carbon Dioxide (CO2) About 2 billion years ago, primitive microscopic single celled forms of life called Phytoplankton began to fill the oceans Another important event during the Precambrian was the appearance of the first single celled forms of life These phytoplankton were very important Because they helped create an oxygen rich atmosphere for life to thrive in These microscopic phytoplankton absorbed CO2 from volcanoes and through Photosynthesis released Oxygen (O2) into our atmosphere As Oxygen fill our atmosphere, Our skies eventually became Blue Precambrian O2 O2 O2 CO2 CO2 CO2

  9. How did our atmosphere become rich in oxygen? Answer Bank Extinction 90% Meteorites Explosion Fossil Oxygen Humans Photosynthesis • Primitive phytoplankton and algae bacteria called stromatolites released oxygen into our atmosphere through _____ about 2 bya

  10. Major Geologic Events of the Precambrian Era 4.5 bya- Moon forms 3.8 bya- first oceans form 3.5 bya- 1st single celled forms of life Precambrian 1.1bya-1st continent Rhodinia forms 1.3 bya- first multi celled forms of life 2 bya- oxygen rich atmopshere forms

  11. What are major geologic events of the Precambrian Era? Answer Bank Extinction 90% Meteorites Explosion Fossil Oxygen Humans Photosynthesis • 3.8 bya- oceans form • 3.5 bya- 1st single celled forms of life • 2 bya- ____ rich atmosphere forms • 1.3 bya- 1st multi celled forms of life • 1.1bya-1st continent Rhodinia forms

  12. Paleozoic Precambrian Paleozoic Era The Paleozoic Era witnessed an explosion of life Very shallow seas covered most of the earth Through out these shallow seas lived some of the first complex forms of life Including: invertebrates (shell fish), fish and plants Some of these animals included trilobites, ammonites (squid like creatures with shells)

  13. Major Geologic Events of the Paleozoic Era Paleozoic Precambrian

  14. Paleozoic Precambrian Major Geologic Events of the Paleozoic Era 245 mya- Mass Extinction 90% of all life 322 mya- First reptiles appear 513 mya- First land plants appear 536 mya- 1st fish & invertebrates appear 570 mya- Explosion of life

  15. What are major geologic events of the Paleozoic Era? Answer Bank Extinction 90 Meteorites Explosion Fossil Oxygen Humans Photosynthesis • 570 mya- _____ of life • 536 mya- 1st fish & invertebrates 513 mya- 1st land plants • 322 mya- 1st reptiles appear • 245 mya- Mass Extinction ___% of all life

  16. Mesozoic Era Mesozoic Paleozoic Precambrian The Mesozoic Era was the age of reptiles & witnessed the evolution of the largest animals to have ever walked the earth The dinosaurs would eventually go extinct and give rise to modern day birds However, as we all know, these dinosaurs died Out and left a world for other animals to inherit

  17. Dinosaur Demise • There is mounting evidence that a large meteorite impact slammed into earth 65 mya ending the Cenozoic era • This impact would have caused widespread devastation and fires

  18. Dinosaur Demise • Ash and smoke from fires could have blocked out enough sunlight changing the global climate; decimating and wiping out the cold blood reptiles

  19. Major Geologic Events of the Mesozoic Era Mesozoic Paleozoic Precambrian

  20. Mesozoic Paleozoic Precambrian Major Geologic Events of the Mesozoic Era 65 mya- Mass extinction 60% of all life perishes 160 mya- First Birds appear 180 mya- Pangea breaks up 200 mya- First Mammals appear 200 mya- First Mammals appear 200 mya- First Mammals appear

  21. What are major geologic events of the Mesozoic Era? Answer Bank Extinction 90% Meteorites Explosion Fossil Oxygen Humans Photosynthesis • Reptiles dominate • 200 mya- 1st small Mammals appear • 180 mya- Pangea breaks up • 160 mya- 1st Birds • 65 mya- Mass extinction 60% of all life perishes including dinosaurs due to large ______collision

  22. Cenozoic Era Cenozoic Mesozoic Paleozoic Precambrian With Dinosaurs gone, Mammals would inherit the earth and dominate the land Large mammals thrive such as Horses, Mammoths, and Primates Mankind would evolve and inhabit the earth expanding it’s population Many Ice Ages came in went causing the extinction of many large mammals

  23. Major Geologic Events of the Cenozoic Era Cenozoic Mesozoic Paleozoic Precambrian

  24. Cenozoic Mesozoic Paleozoic Precambrian Major Geologic Events of the Cenozoic Era 300,000 ya- Modern humans appear 7 mya- First Human Ancestors appear 45 mya- One of the largest Ice ages occur

  25. What are major geologic events of the Cenozoic Era? • Mammals dominate • 45 mya- Major ice age event • 7 mya- 1stHuman ancestors appear • 300,000ya- 1st modern ____ • Present- your writing this down!!!!! (do not write ) Answer Bank Extinction 90% Meteorites Explosion Fossil Oxygen Humans Photosynthesis

  26. Summarize: List the events in order: Oldest to youngest • Mammals dominate the earth • Mass extinction 90% of all life wiped out • Reptiles dominate the earth • Explosion of life • Phytoplankton create oxygen rich atmosphere • Mass extinction 65% of all life wiped out including dinosaurs

  27. Topic: Relative Dating Objectives: Day 2 of 3 • To learn how scientists use relative dating techniques to put geologic events in order • To learn how to apply the laws of geology (the law horizontality, law of superposition, law of cross-cutting relationships) to relative dating

  28. Quickwrite: In 2-3 sentences answer one of the questions below: • How do you think scientists know which fossils are older and which fossils are younger? • Imagine you have a full trash can, where would you find the old trash??? Where would you find the new trash???

  29. Relative Dating • In our last notes, we learned the history of the earth, when reptiles first appeared, when dinosaurs went extinct, when mammals dominated earth • So how do we know the order of all these events? • One way scientist’s have figured out Earth’s History is by Relative Dating “Age of Water and Atmosphere” Precambrain “Age of Plants, fish, and invertebrates” Paleozoic “Age of Reptiles” Mesozoic “Age of Mammals” Cenozoic

  30. Relative Dating 8. • Relative Dating is the concept of dating rocks by putting geologic events in order • It does not give an exact age of rocks 7. 3. 5. Fault cuts through 2. 1. 4. Magma Intrusion

  31. What is Relative Dating? 8. • The concept of dating rocks by putting geologic events in_______ Answer Bank Younger gap Top after Bottom Order flat 7. 3. 5. Fault cuts through 2. 1. 4. Magma Intrusion

  32. Law of Superposition • In layers of deposited sedimentary rock, the oldest rock layers are at the bottom and the rock layers become younger toward the top • Therefore, older fossils would be ath the bottom and younger fossils would be closer to the top 3. 2. 1.

  33. Law of Superposition • Principle of Superposition: States that the oldest rock layers are at the bottom and the rock layers become younger toward the top

  34. The Law of Superposition:Old rocks formed on the bottom and young rocks are at the top Young rocks are at the top Old rocks are at the bottom

  35. What is the Law of Superposition? • In layers of deposited sedimentary rock, the oldest rock layers are at the ____ and the rock layers become younger toward the ____ 3. Answer Bank Younger gap Top after Bottom Order flat 2. 1.

  36. Law of Horizontality Law of Horizontality: Rocks fall into place forming flat, horizontal layers

  37. Law of Horizontality Sediments are originally deposited in flat horizontal layers. If the rocks are folded or are laying at a steep angle, they must have been disturbed or tilted after they were originally deposited. 3. 3. 2. 2. 1. 1.

  38. What is the Law of Horizontality? Sediments are originally deposited in ____ horizontal layers. If the rocks are folded or at an angle, they must have been disturbed _____they were originally deposited. Answer Bank Younger gap Top after Bottom Order flat 3. 3. 2. 2. 1. 1.

  39. Unconformities • Think of layers of rock as pages of a history book • If we remove pages, the book is incomplete • An unconformity is when layers of rock are missing 3. 3. 2. 1. 1.

  40. Unconformities:Here’s how it works!!!! 5. 3. 4. 3.Unconformity (weathering and erosion create a gap in geologic time) 2. 1.

  41. Unconformities • An unconformity is a gap in rock layers due to erosion and weathering or a break in the depositing of sediments (missing rock layers) 3. 3. 2. 1. 1.

  42. What is an Unconformity? Answer Bank Younger gap Top after Bottom Order flat • An unconformity is a ____ in rock layers due to erosion and weathering or a break in the depositing of sediments (missing rock layers) 3. 3. 2. 1. 1.

  43. Law of Cross Cutting Relationships • The law of cross cutting relationships states that a fault line or an igneous intrusion must be younger than the rock it cuts across. 3. 5. Fault cuts through 2. 1. 4. Magma Intrusion

  44. What is the Law of Cross Cutting Relationships? Answer Bank Younger gap Top after Bottom Order flat • A fault line or an igneous intrusion must be _____ than the rock it cuts across. 3. 5. Fault cuts through 2. 1. 4. Magma Intrusion

  45. Practice:Start with the oldest rock and work your way to the youngest Young 1. 2. 3. 4. 5. 6. 7. 8. Old H H H G F E G G D F F C C C B A E Fault cuts through E Fault cuts through B B A A D Magma Intrusion D Magma Intrusion

  46. Practice:Start with the oldest rock and work your way to the youngest Young 1. 2. 3. 4. 5. 6. 7. 8. 9. Old K H H H G F E G G D F F C C C K K B E A E Fault cuts through B B A A D D Magma Intrusion

  47. Summary: • The law of ______ states that Sediments are deposited in flat horizontal layers • When rock layers are missing in the geologic record we call it an _______ • The law of ____ ____ relationships states that A fault line or an igneous intrusion must be younger than the rock it cuts across. Answer Bank unconformity horizontality Cross-cutting superposition

  48. Topic: Absolute Dating Objectives: Day 3 of 3 • I will know how scientists use absolute dating to determine the exact age of rocks • I will know the concept of half life and radioactive decay

  49. Quickwrite: In 2-3 sentences answer one of the questions below: • If you shook up 100 pennies in a box, how many do you think would be heads???? How many do you think would be tails???? • Let’s say you have 100 dollars and you can only spend half of it every day. How much money would you have after 2 days????

  50. Absolute Dating • How do we know the earth is 4.6 billion years old? • How do we know when dinosaurs went extinct? • We can answer those questions by using Absolute Dating • Absolute Dating is a method used by geologists to determine the exact age of a rock or fossil • By analyzing the properties of atoms in rocks and fossils we can get a really accurate date for when the rock or fossil formed “Age of Water and Atmosphere” Precambrain “Age of Plants, fish, and invertebrates” Paleozoic “Age of Reptiles” Mesozoic “Age of Mammals” Cenozoic

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