Bowen's Reaction is a geological concept that describes the sequence of mineral crystallization from molten rock, or magma, as it cools. Named after geologist N.L. Bowen, this reaction series illustrates how different minerals form at specific temperatures. The process begins with the crystallization of olivine at high temperatures, followed by pyroxene, amphibole, and biotite as the temperature decreases. The reaction series is divided into two branches: the discontinuous series and the continuous series. The discontinuous series shows minerals that change composition as they crystallize, while the continuous series illustrates the gradual change in the composition of plagioclase feldspar. Understanding Bowen's Reaction helps geologists interpret the history of igneous rocks.