1. Map, chart, graph refer to representations of surfaces, areas, or facts. Map most commonly refers to a representation of the surface of the earth or a section of it, or an area of the sky: a map of England. A chart may be an outline map with symbols conveying information superimposed on it, a map designed especially for navigators on water or in the air, a diagram, or a table giving information in an orderly form: a chart of the shoals off a coast. A graph may be a diagram representing a set of interrelated facts by means of dots or lines on a coordinate background; or it may use small figures (people, animals, machines, etc.) appropriate to the facts being represented, each figure standing for a specific number in statistics being given: a graph of the rise in population from 1900 to 1980.

Did you mean well-marked?