36 



THE AGE OF THE EARTH 



there is much to suggest its existence * and all the 

 phenomena of mountain ranges become explicable : they 

 begin to present an appearance that invites mathematical 

 treatment ; they inspire us with the hope that from a 

 knowledge of the height and dimensions of a continent 

 and its relations to the bordering ocean we may be able 

 to predict when and where a mountain chain should arise, 

 and the theory which explains them promises to guide us 

 to an interpretation of those world-wide unconformities 

 which Suess can only account for by a transgression 

 of the sea. Finally it relieves us of the difficult}^ pre- 

 sented by mountain formation in regard -to the estimated 

 duration of geological time. 



This may perhaps be the place to notice a highly 

 interesting speculation which we owe to Professor Blytt, 

 who has attempted to establish a connection between 

 periods of readjustment of the earth's crust and variations 

 in the eccentricity of the earth's orbit. Without entering 

 into any discussion of Professor Blytt's methods, we may 

 offer a comparison of his results with those that follow 

 from our rough estimate of one foot of sediment accumu- 

 lated in a century. 



Table showing the Time that has elapsed since the Beginning of 

 the Systems in the first column, as reckoned from Thickness of 

 Sediment in the second column, and by Professor Blytt in the 

 third : 



Vide pp. 11 and 60. 



