Agassiz, (Jean) Louis Rodolphe (1807–1873)

Swiss-born US palaeontologist and geologist who developed the idea of the ice age. He established his name through his work on the classification of fossil fishes. Unlike Charles Darwin, he did not believe that individual species themselves changed, but that new species were created from time to time.

Travelling in the Alps in 1836, Agassiz developed the novel idea that glaciers, far from being static, were in a constant state of almost imperceptible motion. Finding rocks that had been shifted or abraded, presumably by glaciers, he inferred that in earlier times much of northern Europe had been covered with ice sheets. Etudes sur les glaciers/Studies on Glaciers (1840) developed the original concept of the ice age, which he viewed as a cause of extinction, demarcating past flora and fauna from those of the present.

His book Researches on Fossil Fish (1833–44) described and classified over 1,700 species. He conducted many expeditions to the American West, and his Contributions to the Natural History of the United States (1857–62) is an exhaustive study of the American natural environment.

Agassiz was born in Motier and studied at various European universities. He earned a PhD at the university of Erlangen in 1829 and an MD at Munich in 1830. In Paris he adopted the French anatomist Georges Cuvier's pioneering application of the techniques of comparative anatomy to palaeontology. In 1832 Agassiz became professor at the university of Neuchâtel, Switzerland. Moving to the USA in 1846, he delivered a course of lectures on zoology at the Lowell Institute, expounding his theories on the ‘Plan of the Creation’, and in 1848 he was appointed professor of zoology and geology at Harvard.