Isoline

http://legacy.sfei.org/ecoatlas/GIS/MapInterpretation/MapsandScales.html

Featured above is an Isoline map of an a standard volcanic peak with a crater at the top.   By definition, isolines are the same as contour lines, which represent three dimensional surfaces of the world.  This could arguably be considered a contour map as well as an Isoline map.   The isolines have equal intervals that are increasing in elevation as you get closer to the crater and peak of the volcano.  The closer isolines towards the center indicate a more rapid increase in elevation compared to the further spread apart lines.  The tick marks define the depression that is the crater.