Quote:
	
	
		| 
			
				 
					Originally Posted by ariel
					
				 
				... 
  But the epicenter (or initial point)  of such a transition would still be likely to occur at the point of maximal clash between the two, wouldn't it? 
			
		 | 
	
	
 Or the point(s) at which one was (eventually) supplanted by another. Without more information, I don't know how to distinguish geographical from temporal transition.
Ian.