In the eighteenth and nineteenth centuries, the raging geologic debate pitted neptunism against plutonism. The neptunists, led by German mineralogist Abraham Gottlob Werner, believed that the source of all bedrock was a common ancient sea. According to plutonism, most rock had hardened from a huge molten rock mass. Neptunism held that salt came from the sea, and plutonism insisted it was volcanic in origin.
