More Related Content
What's hot
What's hot (20)
Similar to Geological Time Scale.pptx
Similar to Geological Time Scale.pptx (20)
Recently uploaded
Recently uploaded (20)
Geological Time Scale.pptx
- 1. Geologic TimeScale A BRIEF HISTORY OF EARTHSINCE 4.6BILLION YEARS.
- 2. GEOLOGIC TIME SCALE MYA ERA PERIOD EPOCH PLATE TECTONICS LIFE 0.01 Cenozoic “Age of Mammals” Quaternary Holocene Beaches and barrier islands form -Mastadons become extinct -Human culture flourishes -Accelerating extinction of many species 1.8 Pleistocene Ice sheets form -Modern humans develop -Asians arrive and settle the Americas 5.3 Tertiary Pliocene -Volcanic activity in North America and Africa -Grand Canyon forms Hominids develop 23.8 Miocene Sandhills form in S.C. Horses, mastadons, mammoths, tigers, and camels live in South Carolina 33.7 Oligocene Appalachians uplift; erosion increases Cats, dogs, and apes appear 54.8 Eocene Sea levels rise; deposits of marine sediments – limestone in S.C.; land bridges form -Grass spreads widely -Diverse array of animals develop, including whales, rhinos, and elephants 65.0 Paleocene Earthquakes common; Georgia Embayment, Cape Fear Arch forms in Southeast -First horses appear (size of a cat) -Tropical plants dominate 144 Mesozoic “Age of Reptiles” Cretaceous Mass extinction occurs at the end of the period caused by a meteorite impact (Dinosaurs, ammonites and 25% of marine life become extinct) -T-Rex develops but number of dinosaur species decline -Snakes appear and first primates appear -Angiosperms appear 206 Jurassic Western US: orogeny of Rockies; North America continues to rotate away from Africa -First birds appear -Golden age of dinosaurs 248 Triassic -Pangea begins to break apart -Rocky Mountains and Sierra Nevada form First dinosaurs, mammals, crinoids, and modern echinoids appear 290 Permian -Pangea forms -Appalachians rise -90% of Earth’s species become extinct, including trilobites, blastoids, fish and amphibians because of heavy volcanism in Siberia 2 Table of Contents
- 3. 320 Carboniferous Pennsylvanian Great swamps develop (future coal deposits -Reptiles develop from amphibians -Flying insects appear 354 Mississippian Much of North America is under water -First seed plants appear -Sea life flourishes including coral, brachiopods, blastoids, and bryozoa 417 Devonian Acadian Orogeny – SC metamorphism -Dominant animals: fish -Amphibians, evergreens and ferns appear 443 Silurian Extensive erosion First land plants appear and land animals follow 490 Ordovician -Beginning of the construction of South Carolina -Great extinction due to growth of ice caps including in what is now northern Africa -First animals with bones appear -Dominant animals: marine invertebrates including corals and trilobites 540 Cambrian S.C. near the equator; island arc continues to move toward North America -Explosion of life -All existing phyla came into being here -Life forms in warm seas as oxygen levels rose enough to support life -Dominant animals: trilobites and brachiopods 4600 Precambrian (Hadean, Archean, and Proterozoic Ages) Earth takes 10 million years to cool: initial atmosphere escapes into space (H&He) and the core forms (Fe&Ni) Volcanic outgassing of water and carbon dioxide occurred for millions of years, helping to build atmosphere and then oceans At 3 billion years ago, banded iron formation rocks appear due to rising oxygen levels in the atmosphere and sea No life possible as the Earth initially forms 4.6 billion years ago. Simple, single-celled forms of life appear 3.8 billion years ago. They will become more complex and successful over the next 3 billion years: Prokaryotes then Eukaryotes Cyanobacteria begins producing free oxygen (photosynthesis) Paleozoic “Age of Invertebrates” Modified after Carolina Rocks, contributed by J. Westmoreland
- 4. Measuring Time • • • TheGeological time scale is arecord of the life forms and geological events in Earth’shistory. Scientists developedthe time scaleby studying rock layers and fossils world wide. Radioactive dating helped determine the absolute divisions inthe time scale.
- 5. Giving Time aName • Thelargest sectionsare called “eons”. • “Eons” are divided into “eras” (the 2ndlargest section). • “Eras” are divided into “periods”. • ‘Periods’ are divided into ‘epochs”.
- 6. Eons • Largest, most generaldivision of time. • 2 Eons • Theeons are: Cryptozoic (Precambrian) eon and Phanerozoic eon. • Precambrian and Phanerozoic eon both consists of three erasas shown in the figure.
- 7. Eras • • EachEonis broken up into Eras. Major eras in Earth’shistory: • Archean (4600 mya - 2500mya) • Proterozoic (2500 mya - 540mya) • Paleozoic (540mya - 250mya) • Mesozoic (250 mya - 65.5mya) • Cenozoic (65.5 mya – present) *mya refers to million years ago.
- 8. Periods • EachErais divided into even more specificblocks of time calledperiods. • Various geologic events are associated with each period. • Eachperiod is again classified into different epochs.
- 9. How is Time Divided? • • Major changesin Earth’s history mark theboundaries between the sections. Most sections have been divided becauseamajor organism developed or went extinct ineach section.
- 10. Cryptozoiceon(Precambrian time) • • • • • Lastedfrom 540 million years agoto 4600 million yearsago. Oldest and longest (covers almost 90% of earth’shistory). simple organisms- bacteria, algae, protozoa wasborn. Oldest rocks that we know werefound in this eon which dates to about 3.5 billion yearsold. Divided into 2 eras: Proterozoicand Archean era.
- 11. Archean era • Lastedfrom 2500 million years ago– 4600 million yearsago. • Earliest plants (marine algae) developed. • Thefirst life bacteria cameinto existence (3800 million years ago). • The oldest rocks (3500 million years ago) were formed in this era.
- 12. Proterozoic era • Lasted from 540 million years ago to 2500 million yearsago. • Marine invertebrates were probably common, few with shells. • Glaciations took place inthis era, probably worldwide.
- 13. Phanerozoic eon • Beganfrom 540 million years agoand is still continuingtoday. • Divided into threeeras: i) Paleozoic era (Past life) ii)Mesozoic era (Middle life) iii)Cenozoic era (Present life)
- 14. Palaeozoic Era • • • • Began 570 million years ago and ended 250 million yearsago. Divided into 6 periods (Permian, Carboniferous period, Devonian, Silurian, Ordovician,Cambrian). For the first time on Earth, organisms had hard parts (shells, exoskeletons). Evolution and development of pteridophytes, amphibians, reptiles, fishes, wing bearing insects, trilobites etc.
- 15. Mesozoic era • Lastedfrom 250 millionyears agoto 65 million yearsago. • Popularly known asTime of Reptiles. • Divided into three periods: Triassic, Jurassicand Cretaceous. • Dinosaurs, mammals and gymnosperms appeared.
- 16. Cenozoicera • From 65 million yearsago to presentdays. • Divided into twoperiods: Tertiary andQuarterny. • Development of modern mammals, angiosperms and human beings.
- 18. IMPORTANTPERIODSIN THEHISTORY OFEARTH i) Carboniferous Period It lasted from 360 millionyears to 300 Million years. It is animportant period of Paleozoicera. During this period, first reptiles and pteridophytes wereformed and coal plants got spread. The dead bodies got buried inthis period forming the coals that weuse today.
- 19. ii) Permian It lied between 300 million years to 250 million years. It is also an important period ofPalaeozoic era. Largest massextinction happened in thisperiod. Scientists are not surewhat causedthis massextinction (maybe climate change & volcanoes). 90%of oceanlife and 78%of land life died.
- 20. iii) Jurassic Jurassic is an important period of Mesozoic era. It lasted from 250 millionyears ago to 200 million years ago. During this period, first birds and mammals were formed. Gymnosperms were dominating plants. Thedinosaurs were formed in Triassic period reached at their peak in this period.
- 21. iv) Cretaceous It is aperiod of Mesozoic era which lasted from 150 million years agoto 65.5 million years ago. It marked the end of the Mesozoic Eraand the beginning of the Cenozoic Era.All of the dinosaurs and half of the other animals & plants went extinct in this period. Scientists think an asteroid hit Earth, the dustclouds blocked out the sun.Asaresult, plants died, then herbivores,then carnivores.
- 22. v)Quarternery period It is aperiod of Cenozoicera which hasbeen lasting from 1.8 million years agoto present days. In thisperiod, the humans evolved asthe most intelligent creature of earth and took over. It is divided into 2 epochs namely: Pleistocene and Holocene.