STAGES OF THIS RECORD. 275 



lowing arrangement expresses the amount of their infor- 

 mation : 



CAIXOZOIC f Quaternary or Kecent formations. 



(Recent Life.) \ Tertiary. 



MESOZOIO ( Cretaceous or Chalk. 



(Middle Life) 1 Oolitic or Jurassic. 



t Triassic or Upper New Bed Sandstone. 



{Permian or Lower New Red Sandstone. 

 Carboniferous or Coal System. 

 Old Red Sandstone and Devonian. 

 Silurian. 



Eozoic ( Cambrian. 



(Dawn Life.) \ Laurentian. 



In this arrangement the terms Eozoic, Palaeozoic, Mesozoic, 

 and Cainozoic, indicate the chronological stages having re- 

 ference to the ascent of life ; and Laurentian, Cambrian, 

 Silurian, &c., those having reference to the different for- 

 mations whose depositions mark the successive physical 

 operations of nature. By this arrangement the geologist 

 simply asserts that the Laurentian preceded the Cambrian, 

 and the Cambrian the Silurian, but no opinion is expressed 

 as to the amount of time required for the deposition of the 

 Laurentian, or whether the Cambrian occupied a longer 

 time in formation than the overlying Silurian. We may 

 feel convinced, from the total thickness of a system, the 

 alternations of its strata, and the succession of its fossils, 

 that it occupied a much longer time in formation than 

 another system ; but this is not expressed in the above 

 arrangement, which merely affirms a sequence from older 

 to younger, and from the earliest ascertainable operations 

 to those still taking place around us. 



Such is the chronology of Geology a chronology to which 

 investigators endeavour to conform the rock-formations of 

 the globe j and although the Chalk of one country, for ex- 

 ample, may not have been exactly contemporaneous with 



