Geologic time scale

• The longest portions in geologic time

  Eons
• It accounts 88% earth's history

  Precambrian
• Few rocks were deformed and metamorphosed

  Hadean Eon
• It is the period where life first formed on Earth, archea and bacteria

  Archean Eon
• Rifting of the continental crust subsequently filling with sedimentary rocks and volcanic rocks

  Proterozoic Eon
• It means visible life

  Phanerozoic eon
• This period is known as the age of fishes

  Devonian
• Known as the age of dinosaurs

  Mesozoic era
• It is also known as the age of mammals

  Cenozoic era
• It is the subdivision of eons

  Era
• What are the three periods in Cenozoic Era?

  Quarternary, paleogene, and Neogene
• Most earth's climate was tropical. Continents drifted apart creating vast stretches of oceans.It consist of Paleocene,Eocene and Oligocene Epoch

  Paleogene Period
• It gives rise to early primates, it consist of Miocene and Pliicene Epochs

  Neogene period
• It is the most recent period

  It is also termed Anthropogene period

  Subdivided into 2 epochs

  •Pleistocene and Holocene

  Quarternary Period
• When human civilization arose

  Holocene
• Almost all marine organisms came into existence as evidenced by abundunt fossils

  Cambrian period
• What are the two supercontinents in the Cambrian period

  Gondwana and Laurentia
• This period marked the earliest appearance of vertebrates and the jawless fish known Agnatha

  Ordovician Period
• This period brought the emergence of terrestrial life

  Silurian Period
• What is the earliest well developed circulatory system(vascular plants)

  Cooksonia
• What is a primitive armoured fish with a cartilage skeletone is the earliest fish known to have jaws

  Romundina
• A dramatic climatic shift may have been partially triggered the assembly of smaller continents into a supercontinent

  Permian Period
• What gave rise to dinosaurs

  Diapsids
• What gave rise to mammals

  Synapsids
• It tells us the sequence in which events occured, not how long ago they occured

  Relative dating
• Measures the number of radioactive elements in rocks to give the ages to each division of time in geologic time scale

  Absolute dating
• A dramatic climatic shift may have been partially triggered the assembly of smaller continents into a supercontinents

  Parmian Period
• Tells us tge sequence in which events occured, not how long ago they occured

  Relative Dating
• Tells us the sequence in which events occured, not how long ago the occured

  Relative dating