Neptunism

Neptunism, a superseded scientific theory of geology proposed by Abraham Gottlob Werner (1749-1817) in the late 18th century, proposed rocks formed from the crystallisation of minerals in the early Earth's oceans.

The theory took its name from Neptune, the ancient Roman god of the sea. There was considerable debate between its proponents (Neptunists) and those favouring a rival theory known as plutonism which gave a significant role to volcanic origins, and which in modified form replaced neptunism in the early 19th century as the principle of uniformitarianism was shown to fit better with the geological facts as they became better known.

Modern geology acknowledges many different forms of rock formation, and explains the formation of sedimentary rock through processes very similar to those described by neptunism.

In the mid-eighteenth century as the investigation of geology found evidence such as fossils, naturalists developed new ideas which diverged from the Genesis creation narrative. Georges de Buffon proposed that the Earth was over 75,000 years old, possibly much older, and showed signs of historical development in a series of distinct epochs.

Abraham Gottlob Werner was the inspector of mines and professor of mining and mineralogy at the Mining Academy in Freiberg (Saxony) which became dominant in late eighteenth-century geology. His Short Classification and Description of Rocks of 1787 and his lectures set out a classification of rocks on the basis of their age based on the sequence of layers of differing material, rather than by the types of minerals as had been previous practice.

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