Abraham Gottlob Werner

Werner's Neptunist theory proposed that all rocks, including granite and basalt, formed through chemical precipitation and sedimentation from a primordial global ocean. He argued that the Earth's geological features were shaped by the gradual recession and chemical action of this ancient sea. The theory dominated geological thought in the late 18th century before being largely superseded by Plutonism.

Werner taught at the Mining Academy in Freiberg, Saxony, Germany, where he served as a professor of mineralogy and mining. His lectures attracted students from across Europe and the Americas, making Freiberg one of the most influential centers of geological education in the late 18th and early 19th centuries. His students carried his theories and methods to institutions worldwide.

The Neptunist-Plutonist controversy pitted Werner's theory that all rocks precipitated from water against James Hutton's view that igneous processes and heat played a primary role in rock formation. Hutton argued that granite and basalt were of volcanic origin, which Werner disputed. The debate was one of the most significant scientific disputes in the early history of geology and was ultimately resolved in Hutton's favor.

Werner is credited with establishing mineralogy as a rigorous, systematic discipline and with creating one of the first comprehensive schemes for classifying minerals based on their external properties. Though his Neptunist theory was eventually disproven, his teaching methods and classification systems profoundly influenced the development of geology as a science. He is often referred to as the father of German geology.