The answer you have been looking for is “visual”
        
             
        
        
        
The correct answer is: Insulation
I hoped that helped :)
        
                    
             
        
        
        
Formed by erosion created by seafloor spreading
RIVER DELTAS ARE formed by erosion created by seafloor spreading
NOT:
caused by the movement of tectonic plates areas of infertile, rocky soil