CHRONOLOGY OF THE EARTH 



B.C. 



Collision between extinct heavenly bodies, and forma* 

 tion of the Nebula . . ... 



Concentrations in the Nebula, and emergence of the 

 Earth as a molten body 



Long Ages of intense heat of the whole Earth . . 



Surface of the Earth so far solidified as to support 



vast seas . . ... 100,000,000 



Foundational Ages extending over 70,000,000 years. 



Beginning of Cambrian Period 

 ,, Ordovician Period 



,, Silurian Period . 



,, Devonian Period 



,, Carboniferous Period 



,, Permian Period . 



,, Triassic Period . . 



,, Jurassic Period . 



,, Cretaceous Period 



,, Eocene Period . 



,, Oligocene Period . 



,, Miocene Period . . 



Pliocene Period . 



Palaeozoic Age 



Mesozoic Age< 



Cainozoic Age 



Quaternary Age- 



Pleistocene Period 

 Present Period , 



30,000,000 

 24,500,000 

 18,000,000 

 15,000,000 

 13,000,000 

 7,500,000 



7,000,000 

 5,750,000 

 3,500,000 



2,250,000 

 1,750,000 

 1,250,000 

 400,000 



200,000 

 50,000 



(The estimate of the relative durations of the Periods is founded on the thicknesses of 

 the successive geological strata. All dates are conjectural, and the above duration must 

 be regarded as a minimum.) 



