Diagrammatic Map

a simplified map, usually without a grid. The schematic representation makes it possible to form a general idea of the phenomenon or event shown in graphic form on the map and to emphasize its fundamental characteristics. The content of a diagrammatic map is strictly limited to elements that are important for an understanding of the subject. Previously published geographic maps are sometimes used as the basis for a diagrammatic map; the content of the diagrammatic map is drawn onto them in a generalized, schematic form and made very clear.