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Geologic Time

Geologic Time. What is Geologic Time?. A relative scale which divides geologic time into units. Relative time is compared to something. Units are from largest to smallest Eon Era Period Epoch Age. Basis for subdivision. Law of superposition

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Geologic Time

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  1. Geologic Time

  2. What is Geologic Time? A relative scale which divides geologic time into units. Relative time is compared to something. Units are from largest to smallest Eon Era Period Epoch Age

  3. Basis for subdivision Law of superposition Age of Earth 4.6 billion yrs Age of oldest rock 4 billion yrs Extinctions

  4. Precambrian Era Vast time in earth history before the deposition of Cambrian Fossil bearing rocks. Fossils are rare because animals were soft bodied. Example: Jellyfish, paramecium, and trail marks from animals.

  5. Plants and animals

  6. Paleozoic Era Life increased in complexity The continents collided to form Pangea Also has “Age of fishes” in it Divided into 6- 7 periods

  7. Cambrian Period- 600 mya 1st common and widespread fossils example: Algae, sponges, worms, mollusks All lived in the Sea Trilobites- large but few bivalves- clams sea cucumbers

  8. Cambrian environment

  9. Ordovician Period 500-425 mya Rise of new animals groups of importance. Oldest vertebrates- fragments of bone example: bryozoans, brachiopods, echnoids Sea covered land uplift and mountain building

  10. Ordovician environment

  11. Silurian Period 425-405 mya New families rather than new groups of animals Most important plants (fossil of oldest plant) Trilobites, crinoids, etc. from ancient reefs near Chicago types of fish starting

  12. trilobites Live fossil

  13. crinoids live fossil

  14. Silurian Environment

  15. Devonian Period 405-345 mya Expansion of fish and land plants 1st land animals (primitive amphibians) First developed fish Jawless fish plate-skinned fish sharks 1st boney fish From lobed-fin fish -amphibians

  16. Devonian continued Oldest spiders, millipedes and insects Fresh water clams Great forests starting Coral reefs

  17. Devonian environment

  18. Carboniferous 345-280mya Mississippian period 345-310 mya Shallow warm seas Sea animals and plants flourish Amphibians and land plants spread Coal swamp forests (most US under water) Pennsylvanian Period 310-280 mya Scale trees, seed ferns develop Giant dragonflies (30 inch wing span) Reptiles from amphibians

  19. Carboniferous environment

  20. Permian Period 280-230 mya Primitive conifers New insects (beetles, and true dragonflies) Active reptiles different from skull and vertebrae fossil eggs example: sail-back lizard (sail as temperature control) Theriodonts – carnivore ( mammals are descendents) A lot become extinct (trilobites, corals, blastoids)

  21. Permian environment

  22. Mesozoic Era Known as middle Life Also has the “Age of the Reptiles” in it. New pattern of lands and seas, formed mountains ranges

  23. Triassic Period 230-180 mya A lot of volcanic activity Reptiles dominate advanced body structure shell-protected eggs both land and water reptiles 1st appeared lobster like creature Conifer forest- Petrified forest

  24. Triassic Environment

  25. Jurassic Period 180-145 mya Flying reptiles and herbivores in water Oldest mammals-fragments of rat sized jaws and teeth. Oldest known bird Over thousand species of insects

  26. Dinosaurs 3 main groups 1. Sauropods: long-necked, long-tailed, four-legged (largest land animal 87 ft long) 2. Stegosaurs: armored reptiles, weighed up to 10 tons 3. Carnivorous Theropods: walk on hind legs

  27. Dinosaurs hips Dinosaurs are also classified by the two types of hips. Saurischian- lizard hipped ornithischian- bird hipped

  28. Cretaceous Period 135-63 mya Major advanced of sea New arrivals- flowering plants, trees-magnolia, oaks, maple, etc. New sources of food provided for mammals, birds, reptiles, and insects Dinosaurs roamed over all continents Small mammals, marsupials At the end of period extinction of dinosaurs.

  29. Cretaceous Environment

  30. Cenozoic Era 63-1 mya ( last 70 my) Two Periods and seven epochs Includes the age of the Mammals Includes the age of Man Birds are numerous Boney fish dominate Our era of today

  31. Tertiary Period Has five epochs. A lot of changes taking place examples: -Small mammals to large mammals -Tropical plants to grasses -Single animals to herds -Alps, Himalayas, Rockies, Andes and Glacier formation

  32. Paleocene epoch Mammals are small Tropical plants

  33. Eocene Epoch Mammals becoming larger Ancestors of modern whale and horse

  34. Oligocene Epoch Tropical plants replaced by grasses and pines Apes, elephants, cats and dogs families

  35. Miocene Epoch Herds of grass eating animals Land bridge between Siberia and Alaska- Mastodans cross.

  36. Pliocene Epoch Glaciers began to form Sea level fell Animals crossed land bridges and new land formed Animals hunting herds (Near End of Epoch) Ice age begins Grand canyon was carved out of rising rock layers

  37. Grand canyon layers

  38. Quarternary Period Includes two Epochs Climate much colder Includes the Ice Age Includes the age of man Our period of today

  39. Pleistocene Epoch 2.5 mya Ice Age Glaciers advanced at least four different times Animals either developed protective covering or moved south example: mastodons, saber-tooth tigers, mammoths (At end of the epoch) 10,000 yrs ago Ice sheets melting Large mammals became extinct

  40. Pleistocene environment

  41. Holocene Epoch Earth’s climate became warmer Human civilization arose (Age of man) The epoch of today

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