I'd have to say Geometry is actually more abstract than algebra because of the visuals.  I guess Algebra could be looked at as more abstract because the idea of a letter or variable means that any number or a set of numbers could substitute a letter/variable that represents a certain kind of mathematical relationship/pattern that always occurs.
				
			 
				 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		