Geological Time Scale

on

 



    4.6BY : Earth Formed

 

    PRECAMBRIAN EON

 

    ARCHEAN ERA: From 4.1 to 2.5 BY

     (1)   Eoarchean: 4.1 to 3.6 BY

     (2)   Paleoarchean: 3.6 to 3.2 BY

     (3)   Mesoarchean: 3.2 to 2.8 BY

     (4)   Neoarchean: 2.8 to 2.5 BY

 

Characteristics:

·        Early bacteria and algae (Stromatolites)

·        Cratons formation took place {e.g.- Dharwar, Bastar, Singhbhum, Aravalli(Mewar and Marwar) and Bundelkhand}.

 

 

  PROTEROZOIC ERA: From 2.5 BY(2500MY) to 541 MY

 

     (1)   Paleoproterozoic: 2.5 to 1.6 BY

     (2)   Mesoproterozoic: 1.6 to 1 BY

     (3)   Neoproterozoic: 1 BY(1000MY) to 541MY

 

Characteristics:

·        This era starts from simple multicellular organisms and ends at complex multicellular organisms.

·        Columbia(Nuna) orogeny: 2.0 to 1.8 BY

·        Rodinia orogeny(Grenville orogeny): 1.3 to .9 BY

·        Proterozoic Mobile belts(Aravalli-Delhi MB, Satpura, Shillong)

·        Proterozoic Sedimentary basins(e.g.- Cuddapah and Vindhyan)

 

 

  PHANEROZOIC EON

 

   PALEOZOIC ERA: From 541 to 251 MY

     (1)   Cambrian Period: “Age of marine invertebrates”

·        Early shelled organisms

     (2)   Ordovician Period: Trilobita maximum, Primitive fishes etc. 

     (3)   Silurian Period: First Land Plants 

     (4)   Devonian Period: “Age of fishes” and first amphibians appeared

     (5)   Carboniferous Period: Composed of Mississippian and Pennsylvanian, “Age of Amphibians” and famous for coal forming swamps.

     (6)   Permian period:

 

Characteristics:

·        Gondwana(Pan African)orogeny

 MESOZOIC ERA: From 251 to 66 MY

Also called “Age of Reptiles”

 

     (1)   Triassic Period: First dinosaurs, first mammals

     (2)   Jurassic Period: “Age of Dinosaurs” and flowering plants

     (3)   Cretaceous Period: Extinction of Dinosaurs and due to large volcanic activities; Volcanic plateau formed (e.g.- Deccan Plateau in India, Siberian Plateau in Russia and Columbia Plateau in USA)

 

 CENOZOIC ERA: From 66 MY- Present

Also called “Age of Mammals”

 

     (1)   Tertiary Period: Includes two periods which contains epoch

        a)Paleogene period

  •   Paleocene Epoch
  •   Eocene Epoch
  •  Oligocene Epoch

       b)Neogene period:

  • Miocene Epoch
  •  Pliocene Epoch

 

Characteristics: Formation of young fold mountains(Himalayas, Alpine orogeny)   

  

     (2)   Quaternary Period:  Pleistocene Epoch(Ice Age), Holocene Epoch

 

Mass Extinction Event: A rapid decrease in biodiversity of Earth.

·        1) Ordovician-Silurian

·        2) Devonian-Carboniferous

·        3) Permian-Triassic

·        4) Triassic-Jurassic

·        5) Cretaceous-Paleogene 

       { BY-Billion Years Ago, MY- Million Years Ago}


    Peace Out

    -Ichbinaasif




Comments

Post a Comment