Module 9 - Cartography - Isarithmic Mapping

Isarithmic Map:  Continuous Tones

This week's exercise in Introduction to Cartography involved generating maps with Isarithmic data symbolization.  This precipitation data for the State of Washington is of smooth and continuous nature over the whole area.  Measurements are taken at control points, then the data is interpolated to form contours, or lines of equal value.  A color scheme can be used to further clarify the data.







In the first map, the values in inches of participation are continuous, or non-classed. This method is precise because it represents very fine divisions by many slightly different hues.
 In the second map, ranges of precipitation have been divided into classes, and the representative colors are more distinct from one another.  It is not as precise, but it is easier to evaluate in a general way.
Contouring is yet another isarithmic method to represent changes in values over an area, and it has the advantage of being easily replicated in black ink only.

Isarithmic Map: Hypsometric Tints and Contours

Isarithmic maps are useful in many natural resources applications such as petroleum exploration, hydrology and mining because they are ideal for depicting elevation, depth, thickness, chemistry, and many other physical properties typically examined in the evaluation of natural resources.