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Comprehensive Outline of Divisions in Geological Time Scale (for UPSC CSE)
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In this lesson, Bhumika has done an in-depth analysis of divisions of Geological time scale. She has explained comprehensively about the Pre- Cambrian era, and Paleozoic era. followed by this she illustrates how the early land plants and fish appeared. She then speaks about the Mesozoic era and the Mesozoic mammals. She also emphasizes on certain facts pertaining to mass extinction event which happened in Mesozoic era. Lastly, she gives a comprehensive outline of Cenozoic​ era .

Bhumika Saini
B Tech from MNIT, Jaipur. Appeared in CSE interview thrice. Loves teaching and playing badminton.

U
Unacademy user
Abhishek Kumar
2 years ago
welcome
madam ji wat is NEOZOIC isn't that called present day...
Ak
mam I have really enjoyed your lessons. your presentation style is also very interesting and easily understandable. please keep your efforts continue mam.. thank you so muchh .
PB
very nice mam.keep the good work
  1. GEMHOLOGY ORIGNAND COURSE: GEOMORPHOLOGY-ORIGINAND EVOLUTION OF EARTH AND RELATED THEORIES LESSON: GEOLOGICAL TIME SCALE-PART 2 PRESENTED BY BHUMIKA SAINI


  2. About me .B Tech from MNIT, Jaipur Interests: Reading, Playing Badminton Appeared in CSE interview thrice Three years of experience in teaching .Course fee: CONTRIBUTE Follow me on Unacademy: https://unacademy.in/user/BhumikaSaini


  3. THE GEOLOGICAL TIME SCALE . The geological time scale (GTS) is a system of chronological measurement that describes the timing and relationships between events that have occurred throughout Earth's history. Scientists developed the time scale by studying rock layers and fossils world wide. . Radioactive dating helped determine the absolute divisions in the time scale.


  4. DIVISION OF GEOLOGICAL TIME SCALE EPOCH PERIODEPOCH EPOCH EPOCH EPOCH ERA EON PERIOD ERA PERIOD


  5. Era Epoch of years Quat Quaternary o.0 Millions of years ago Min Pleistocene Eon Era Pliocene 5.3 enozoic Cenozoic 3 65 Phanerozoic 251 Eocene 8 Paleocene 2 65.5 Neoprot retaceous 145.5 45.s 45.5 Mesopro terozoic Mesozoic 600 Triassic Permian Pennsyivanian 318 Mississippian Mesoarchean 3200 Devonian Paleoarchean Paleozoic Situri Eoarchean Ordovi ician Hadean Preca


  6. PRE CAMBRIAN ERA Started 700 million years before present Earth changed from gaseous to liquid state Marine grasses evolved Soft bodied invertebrate animals evolved in warm seas but land areas devoid of animals


  7. PALEOZOIC ERA (ANCIENT LIFE) The Cambrian period is the 1st period of the Paleozoic Era . Explosion of life in the oceans began during this era. .Most of the continents were covered in warm, shallow seas. . Invertebrates were dominate . Fish emerged during this time . Fish led to the arrival of amphibians . The end of the Paleozoic era is called the "Age of Amphibians" Early land plants including mosses, ferns and cone-bearing plants The early coal forming forests were also formed during this time.


  8. EARLY FISH Early fish did not have jaws. Some species of sharks were in existence at this time.


  9. EARLY LAND PLANTS Ferns Mosses


  10. PALEOZOIC ERA . At the end of the Paleozoic, the largest mass extinction in history wiped out approximately 90% of all marine animal species and 70% of land animals. Possible causes of this Mass Extinction Event Lowering of sea levels when the continents were rejoined as Pangaea (convergent boundary) e Increased volcanic activity (ash and dust) . Climate changes - cooler climate


  11. MESOZOIC ERA - MIDDLE LIFE Athe beginning of this era the continents were joined as Pangauea. At the beginning of this era the continents were joined as Pangaea Pangaea broke up around the middle of this era. Reptiles became the most abundant animals because of their ability to adapt to the drier climate of the Mesozoic Era Skin maintains body fluids .Embryos live in shells


  12. MESOZOIC ERA Dinosaurs were also very active in this era. First small dinosaurs appeared in the Triassic Period. Larger and more abundant dinosaurs appeared in the Jurassic Period Small mammals and birds also appeared during this era The mammals were small, warm-blooded animals. Hair covering their bodies These characteristics help them survive in changing environments.


  13. DINOSAURS


  14. MESOZOIC ERA MASS EXTINCTION EVENT .Asteroid or Comet collides with Earth. Huge cloud of smoke and dust fills the air . Huge cloud of smoke and dust fills the air . Blocks out sunlight Plants die . Animals that eat plants die . Animals that eat p Animals 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.


  15. CENOZOIC ERA -RECENT LIFE . Began about 65 million years ago and continues today!!!!! Climate was warm and mild. . Marine animals such as whales and dolphins evolved. Mammals began to increase and evolve adaptations that allowed them to live in many different environments - land, air and the sea. . Grasses increased and provided a food source for grazing animals Many mountain ranges formed during the Cenozoic Era .Alps in Europe and Himalayas in India; Rocky Mountains in the USA


  16. CENOZOIC ERA Growth of these mountains may have helped to cool down the climate Ice Ages occurred late in the Cenozoic Era (Quaternary Period). . As the climate changed, the animals had to adapt to the rise and fall of the oceans caused by melting glaciers. This era is sometimes called the "Age of Mammals"


  17. CENOZOIC ERA Marine animal examples: . Algae, Mollusks, Fish and Mammals Algae, Mollusks, Fish Land animal examples: Bats, Cats, Dogs, Cattle and Humans Humans are thought to have appeared around 3.5 million years ago (during the most recent period - Quaternary) .Flowering plants were now the most common plant life.


  18. CENOZOIC MAMMALS


  19. THANK YOU