geological scale geological scale powerpoint
- 8. The Geologic Time Scale 4.6 Billion Years of Earth History
- 11. What is the Earth’s time scale? • The Geological time scale is a record of the life forms and geological events in 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.
- 13. Divisions of Geologic Time • Eras are subdivided into periods...periods are subdivided into epochs. Era Period Epoch E + P = EP
- 14. Divisions of Geologic Time • Geological time begins with Precambrian Time. Precambrian time covers approximately 88% of Earth’s history.
- 16. One Super Eon and Four Eras • PRE-CAMBRIAN Super Eon – 88% of earth’s history • Paleozoic (ancient life) – 544 million years ago…lasted 300 million yrs • Mesozoic (middle life) – 245 million years ago…lasted 180 million yrs • Cenozoic (recent life) – 65 million years ago…continues through present day
- 17. Today… • Today we are in the Holocene Epoch of the Quaternary Period of the Cenozoic Era. Which unit is the largest? Which unit is the smallest?
- 19. Paleozoic Era (Ancient Life) • “The Age of Fish” • Starts: Cambrian period is the 1st period of the Paleozoic Era. • “Explosion” of life in the oceans began during this era. • Most of the continents covered in warm, shallow seas. – Invertebrates were dominant - Trilobites – Fish emerged during this time – Fish led to the arrival of amphibians – Early land plants including mosses, ferns and cone-bearing plants. – The coal forming forests grew during this time (Carboniferous Period)
- 20. Paleozoic Era Con’t • The Appalachian mountains were formed during this time. • The formation of Pangaea, as the Earth's continents came together once again. • Ends: Permian Period • the largest mass extinction in history wiped out up to 97% of all life on Earth. – Possible causes of this Mass Extinction Event • Lowering of sea levels when the continents were rejoined as Pangaea (convergent boundary) • Increased volcanic activity (ash and dust) • Climate changes – cooler climate
- 21. Trilobites • • • Lived in Earths' ancient seas Extinct before the dinosaurs came into existence Cambrian Period is know as the “Age of the Trilobites”
- 22. Eurypterids (New York State Fossil) Giant Sea Scorpion- largest known arthropods to ever live
- 23. Brachiopods • Marine animals that resemble bivalves such as clams.
- 24. Early Fish Early fish did not have jaws. Some species of sharks were in existence at this time.
- 25. Frilled Shark that was found in Japan in January 2007. This shark was considered a “living fossil”
- 26. Early Land Plants Cone bearing plants Ferns Mosses
- 27. Mesozoic Era (Middle Life) • “The Age of Reptiles” • Start: Triassic Period • Pangaea is still joined together, 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
- 28. Mesozoic Era • Dinosaurs were 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.
- 31. Mesozoic Era • The main plant life of this time were Gymnosperms or plants that produce seeds, but no flowers. – Pine Trees • Flowering plants appeared during the END of this era. • End: Cretaceous Period • 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.
- 34. Mesozoic Mammals
- 35. Mesozoic Plants Flowering plants evolved towards the end of the Mesozoic Era.
- 36. Cenozoic Era (Modern Life) • “Age of Mammals” • Start: Paleocene Period • Starts 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
- 37. Cenozoic Era • 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. • Marine animal examples: – Algae, Mollusks, Fish and Mammals • Land animal examples: • Bats, Cats, Dogs, Cattle and Humans
- 39. Flowering Plants were common during the Cenozoic Era