10 UNIFORM ITARIANISM AND ACTUALlbM 



Uniformitarianism does not deny that sudden catastrophes may 

 occur. But they are never world wide, nor is their effect comparable 

 to the gradual changing of the earth due to actualistic processes of 

 small immediate effect, but operating ov^r large time-spans. So into 

 the philosophy of uniformitarianism there entered a conception of 

 the extremely long time-spans available for geologic processes. 



TIME IN GEOLOGY 



Realisation of the large quantities of time consumed by the geologic 

 history of the earth, gradually helped to form a general acceptance 

 of actualistic thought. In the early days, long before absolute dating 

 techniques were discovered, this was, of course, nothing that could 

 be definitely proved. As so many things in geology, it could only be 

 made to look probable, or perhaps even acceptable, by a rather 

 subjective interpretation of some factual data. More than anything 

 else, I think it is LyelTs description of old temples around Naples, 

 which have been temporarily inundated through slow changes in 

 altitude relative to the water level of the Mediterranean, which sold 

 the idea of the big effect of small causes, if only consistently at work 

 over long enough periods. 



Eternity, a Chinese parable tells, can be hinted at in the following 

 way. In a far northern country' a rocky mountain is visited once a 

 century by a small bird which, in cleaning, scrapes its bill on the 

 stony hill. When the mountain has been worn down from the scraping 

 of that small bird's bill, once every century, one second of eternity 

 has elapsed. The Chinese poet was no geologist, because a geologist 

 sees a great number of smaller processes continuously operating at 

 present, which, although unnoticed by the casual poet, have a far 

 greater effect than the polishing of that little bird's bill. Amongst 

 others, and when no other forces are at work, mere erosion will wear 

 down that mountain far more quickly. 



Time, it follows from this juxtaposition of a Chinese poet and a 

 sceptical geologist, time is the uniformitarianists' biggest ally. Given 

 enough time, earth movements of 1 mm a year, or even 1 mm a 

 century, can create mountains or oceans. Given enough time, a new 

 fauna may develop gradually out of an older one, whilst the older 

 forms die out almost imperceptibly. Given enough time, series of 

 repeated small earthcjuakes will also build mountains or sink parts 



