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Earth’s History

Earth’s History. The Big Idea: Rock, fossils, & other types of natural evidence are used to study Earth’s history & measure geologic time. Unit 2 Lesson 4 The Geologic Time Scale. Once Upon a Time.

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Earth’s History

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  1. Earth’s History The Big Idea: Rock, fossils, & other types of natural evidence are used to study Earth’s history & measure geologic time.

  2. Unit 2Lesson 4 The Geologic Time Scale Once Upon a Time • Geology-study of the origin, history, and structure of Earth and the processes that shape it. http://geology.isu.edu/Digital_Geology_Idaho/

  3. Unit 2 Lesson 1 Geologic Changes Over Time Lesson 4 The Geologic Time Scale Been There, Done That • Uniformitarianism -geologic processes that happened in the past can be explained by current geologic processes. (i.e. volcanoes and erosion) • Scientist believe the Earth is 4.6 billion years old. • James Hutton- proposed uniformitarianism • Catastrophism-states that all geologic change occurs suddenly. (i.e. asteroid hitting the earth)

  4. Unit 2 Lesson 1 Geologic Changes Over Time Fossils -traces or remains of organisms that lived long ago. • Trapped in amber • Trapped in asphalt • Buried in rock • Become frozen • Become petrified http://www.city.kashiwara.osaka.jp/jichisuishin/english/sub-e3.htm http://www.sheppardsoftware.com/Europeweb/factfile/Unique-facts-Europe28.htm http://www.aliexpress.com/compare/compare-amber-fossils.html

  5. Unit 2 Lesson 1 Geologic Changes Over Time Trace fossils-fossilized structure that formed in sedimentary rock by animal activity on or in soft sediment (like mud) • Tracks • Burrows • Coprolite – animal dung http://community.siyavula.com/life-sciences-gr-10/diversity-change-and-continuity/lifes-history/2.5-fossils http://www.answers.com/topic/ediacaran-biota-1

  6. Unit 2 Lesson 1 Geologic Changes Over Time Continents Move • Pangaea –single landmass; broke apart about 200 mya. Evidence • Rock types • Mountains • Fossils Landforms Change over time • Continental plates collide, mountain ranges form. • Plates pulled apart magma is released in volcanic eruptions can occur. • Grinding pass each other, earthquakes can occur. • Jagged mtns undergo erosion/weathering turning into rounded and lower mountains.

  7. Unit 2 Lesson 1 Geologic Changes Over Time Back to the Future • Climate -describes the weather conditions in the area over a long period of time. • Pages 88-89 • Trees • Sea-floor sediments • Ice cores http://jannatwrites.wordpress.com/2011/09/25/what-if/

  8. Unit 2Lesson 2 Relative Dating Who’s First? • Relative dating-used to determine whether an object or event is older or younger than other objects or events. • Sedimentary rocks form when new sediments are deposited in horizontal layers on top of older rock.

  9. Unit 2 Lesson 2 Relative Dating • Law of superposition -younger rocks lie above older rocks if the layers have not been disturbed. Disturbed Rock Layers(page 96) • Tilting- layers become slanted do to layers moving up or down unevenly. • Folding-bending of rocks when squeezed • Faults-break or crack where rock can move • Intrusions-igneous rock that forms when magma is injected into rock & then cools/hardens.

  10. Unit 2 Lesson 2 Relative Dating • Unconformity - missing layer of rock that forms a gap in the geologic record. • Rock layers eroded • Sediment is not deposited for a long time http://legacy.belmont.sd62.bc.ca/teacher/geology12/photos/structural/

  11. Unit 2 Lesson 2 Relative Dating Law of Crosscutting • Layers of rock have to be in place before anything can disturb them • Faults or intrusion must be younger then body cuts through

  12. Unit 2 Lesson 2 Relative Dating • Geologic column-ordered arrangement of rock layers based on the relative ages of the rocks, with the oldest rocks at the bottom. • Fossils of a more recent organism will be in rock that is above/below rock containing fossils of older organisms.

  13. Unit 2Lesson 3 Absolute Dating It’s About Time! • Absolute dating - Determining the actual age of an event or object in years • Proton- (+), nucleus • Neutron- neutral (no charge) nucleus • Electron- (-) outside of the nucleus http://www.universetoday.com/82128/parts-of-an-atom/

  14. Mini Chemistry Lesson • Isotope-different # of neutrons than protons • Atomic mass-the average of the masses of the naturally occurring isotopes • Mass #- neutrons + protons http://www.geog.ucsb.edu/~williams/Isotopes.htm

  15. Unit 2 Lesson 3 Absolute Dating • Radioactive Decay -isotopes that are unstable and break down into other isotopes • Half-life-time needed for ½ of a sample of a radioactive element to undergo radioactive decay and form daughter isotopes. • Radiometric Dating -Finding the absolute age of a sample by determining the relative percentages of a radioactive parent isotope and a stable daughter isotope Page 109 Do the math problem on page 110

  16. Unit 2 Lesson 3 Absolute Dating http://minerals.cr.usgs.gov/gips/na/radio.html

  17. Unit 2 Lesson 3 AbsoluteDating

  18. Unit 2 Lesson 3 AbsoluteDating Sedimentary Rock • Scientists have found that particular types of fossils appear only in certain layers of rock. • Index fossils- used to estimate the absolute age of the rock layers in which they are found. • Present in rock found over a large region • Cleary distinguishing features • From an organism that lived only a short time period in Earth’s history • Occur in large #’s within rock layers

  19. Unit 2 Lesson 4 Geologic Time Scale Once Upon a Time Geologic time scale-divides Earth’s geologic history into intervals of time defined by major events or changes on Earth. • Eons • Eras • Periods • Epochs The largest unit of time is the eon

  20. Unit 2 Lesson 4 Geologic Time Scale The Four Eons 1. Hadean Precambrian 2. Archean Eon 3. Proterozoic 4. Phanerozoic present eon • Geologic time scale have no fixed lengths. Many divisions are based on events in Earth’s geologic history. Some division are based entirely o the fossil record. http://www.ucmp.berkeley.edu/exhibit/histgeoscale.html

  21. Unit 2 Lesson 4 Geologic Time Scale • Paleozoic- • Cambrian • Ordovician • Silurian • Devonian • Carboniferous • Permian • Mesozoic • Triassic • Jurassic • Cretaceous http://www.gonedigging.net/outreach/geological-timelines/attachment/geologic-time-scale-650-mya/

  22. Unit 2 Lesson 4 Geologic Time Scale • Cenozoic- • Tertiary Period Epochs • Paleocene • Eocene • Oligocene • Milocene • Pliocene • Quaternary Period • Pleistocene • Holocene-Humans appear http://web.eps.utk.edu/courses/HistoricalGeo/geotime.html

  23. http://www.docstoc.com/docs/126548145/The-Precambrian-Era_-_The-most-important-era-ever_http://www.docstoc.com/docs/126548145/The-Precambrian-Era_-_The-most-important-era-ever_ Unit 2 Lesson 4 Geologic Time Scale Precambrian Events • Cyanobacteria release oxygen to form atmosphere • First oceans formed • Makes up about 88% of Earth’s history • End of Precambrian was when first animals with exoskeletons appear

  24. Unit 2 Lesson 4 Geologic Time Scale Paleozoic Events • Continents come together to form the supercontinent Pangaea • Plants began to colonize the continents • Era ended with a HUGE mass extinction event: between 90-95% of marine species & 70% of land species disappeared. http://www.corzakinteractive.com/earth-life-history/412_ordovician.htm

  25. http://tabibeasley.blogspot.com/2011/04/did-you-know.html Unit 2 Lesson 4 Geologic Time Scale Mesozoic Events • Break up of Pangaea • Mid-Atlantic ridge forms • Tectonic activity folds earth’s crust, forms mtns. • Dominated by dinosaurs • Mass extinction of dinosaurs ends this era-thought to have been caused by asteroid.

  26. Unit 2 Lesson 4 Geologic Time Scale Cenozoic Events • Continents assume their current positions • Himalayas formed • Alps formed • Quaternary Period characterized by the ice age and the evolution of modern humans http://geography.howstuffworks.com/asia/the-himalayas.htm http://encyclopediaurantia.org/cenozoic.htm

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