1877.] The Rev. S. Hanghton on Physical Geology, 545 



At this rate of geological change the total time required for the manu- 

 facture of Asia and Europe would be 



69 x 5280 x 13718=4997,600,000 wabbles, 



=4170 million years. 



Assuming the minor limit of the epoch of the elevation of the nuinmu- 

 litic limestone to be 640,000 years, we can assign an approximate minor 

 limit to the whole period during which stratified rocks have been forming 

 on the surface of the globe, assuming the rate of deposition to have been, 

 on the whole, constant. 



The following Table gives the approximate thickness of the several 

 geological strata in Europe : — 



feet. 



1. Eozoic 26,000 



2. Lower Paleozoic .-. ..{ ^ ower ^ urian 2 f'™° 



I Upper Silurian 5,500 



["Devonian 9,150 



3. Upper Paleozoic .... J Carboniferous 14,600 



1 Permian 3,000 



^Triassic 2,200 



| Jurassic 4,590 



4. Neozoic ^ Cretaceous 11,283 



| Nummulitic 3,000 



iTertiary 6,000 



Total 110,323 



The proportion which the total thickness of strata bears to that of 

 the Tertiary beds is as 



110,323 to 6000. 

 Hence the minor limit assignable to geological time is 

 110323 x 640730 



6000 



11,700000 years, 



or 12 million years in round numbers. 



It is extremely improbable that the continent of Asia and Europe was 

 formed per saltum, and therefore our minor limit of time is probably far 

 short of the reality. 



If Europe and Asia were formed in a million years, which, is 27| times 

 as rapid as supposition No. 1, the total duration of geological time would 

 be nearly 37 millions of years. 



"Whatever may have been the time actually employed in the manufac- 

 ture of Asia and Europe, that process must have increased the length of 

 day by an amount which may be thus calculated : — 



