Ammers, Ammer of Amer betekende vroeger: waterloop.
Ammers Ammer or Amer used to mean: watercourse.
So Amer doesn't necessarily have to point at the Eem river in Utrecht. It could just as well be an area with many 'watercourses', like the area of Waal, Rhine and Maas, or the area you see in that yellow map I posted (horizontal ellipse).
Edited by Abramelin, 22 March 2013 - 07:05 PM.