Isopleths

Isopleths are lines that represent a constant value of a given variable on a map. Unlike other isoline maps (with the exception of isopachs which do not fluctuate as often) isopleths are normally much more constant in their readings. This map shows hydrogen ion concentration as pH (acid rain) in the U.S. in 1998. The map shown is also planimetric, chloropleth, thematic, and an isoline map.

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