Nicolas DesmarestDied 28 Sep 1815 at age 90 (born 16 Sep 1725).French geologist and geographer whose discovery of the volcanic origin of basalt disproved the Neptunist theory that all rocks were formed by sedimentation from primeval oceans. Studying the Auvergne of central France (1763-74), he found large basalt deposits that he traced as lava flows from nearby ancient volcanoes. He further showed that many valleys are formed by the erosion of the rivers that flow in them. From 1757, Desmarest was employed by the government to help spread better manufacturing methods throughout France. By 1788 he had risen to the post of inspector general and director of manufactures. In 1792, during the French Revolution, Desmarest was imprisoned and narrowly escaped execution.Image: Basalt rock of the Devil's Tower, Wyoming, USA, is an ancient volcanic intrusion left over after all of the overlying material has been eroded away. |
