World 10 1 temp 1334819736 4f8fbb98 620x348 1

geological timescale. Pablo Villarreal

By Pablo Villarreal 2001

  • Precambrian time 4600 ma

    10 The presence of stromatolites indicates that shallow seas covered much of earth during intervals in this period.
    11.Nearly half of the valuable mineral deposits in the world occur in the rocks of this period.
  • Period: to

    P. Villarreal. P8

    geological timescale

  • Cambrian time 542 ma

    23 Shelled brachiopods appear.
    1. There is very little plant life during this period.

  • Ordovician time 488 ma

    1. Colonies of tiny invertebrates called graptolites florished and vertebrates appea, fish did not have jaws or teeth and their bodies were coverd with bony plates.
    2. Trilobites appear.

  • Silurian time 444 ma

    1. Vascular land platns and animals, such as scorpions begin to evolve on land.
    2. Eurypterids, see stars and coral become more common.

  • Devonian time 416 ma

    1. Age of fishes, fish that can breath out the water and spend time on land form.
    2. huge plants begin to develop, early amphibians form.

  • Mississippian period 359 ma

    2.swamps and forests cover the land.

  • Pennsylvanian Period 318 ma

    1. Coal deposits form.
    2. giant coackroches apper.

  • Permian time 299 ma

    1. Environment change causes mass extinction of sea invertibrates as the seas retreat.
    2. Appalachian mountains are created because of collision of tectonic plates and savannahs form.

  • triassic time 251 ma

    1. Welcome to the world of the dinosaur! enter the squirrel sized dinosaur and the first forest dwelling mammals appear.
    2. Ichthyosaurs are living in the ocean, new invertebrates call ammonite develop.

  • Jurassic time 200 ma

    13, Whoa those dinos are getting big and dominate the land-lizard-hipped and bird hipped-carnivors and herbivors have arrived.
    3. Flying reptiles called pterosaurs are in the air now.

  • Cretaceous time 146 ma

    1. first flowering plants appear.
    2. Impact hypothesis- dinosaurs extinct.

  • Paleocene time 65.5 ma

    1. world wide temperatures drop about 4 degrees celsius.
    2. First primates evolve.

  • eocene time 55.8ma

    1. Small rodents evolve.
    2. Flying squirrels, whales and bats appear.

  • Oligocene time 33.9 ma

    1. Many early mammals become extinct, clams and snails flourished.
    2. Himalayas develop due to upliftingcaused by the indian subcontinent and eurasian continents colliding

  • miocene time 23 ma

    1. Antartic icecaps begin to form.
    2. Mediterranean sea dries up and refills several times due to tectonic forcesa dn dropping sea levels.

  • Pliocene time 5.3 ma

    1. First modern horses appear.
    2. Various species migrated between continents across land bridges.

  • Pleistocene time 1.8 ma

    20.Species that did not evolve to survive extreme cold ,oved to warmer climate areas or became extinct.
    9. Homosapien appear and are hunters.

  • Holocene time 0.0115 ma

    1. The last glacial period ended and sea levels rose, great lakes formed.
    2. Modern humas develop agriculture and used tools made of iron and bronze