Jean Louis Rodolphe Agassiz was born in Switzerland in May 1807. He adopted medicine as his profession and studied successively at the universities of Zurich, Heidelberg, and Zurich. He also trained in natural history. In 1829 Agassiz received the degree of Doctor of Philosophy at Erlangen, and in 1830 that of Doctor of Medicine at Munich. Shortly afterwards, Agassiz moved to Paris where he was came under the influence of Alexander von Humboldt and Georges Cuvier; they launched him on his careers of geology and zoology, respectively. Agassiz specialized in icthyology, which interestingly was not the occupation for which he is most remembered. Building on the work of de Saussure, Venetz, and Charpentier in the Alps, he was the first person to scientifically propose, in 1837, that the Earth had been subject to a past ice age. Charpentier had earlier reported that erratics scattered over the slopes and summits of the Jura Mountains had been moved there by glaciers. Based on this conclusion, Agassiz made several trips with Charpentier to the alpine regions of Europe. These investigations led to the publication, in 1840, of Agassiz's seminal work entitled Etudes sur les glaciers ("Study on Glaciers"). In it, he discussed the movement of glaciers, their erosive effects, and the landforms they produced. He accepted Charpentier's idea that some of the alpine glaciers had extended across the wide plains and valleys drained by the Aar and the Rhone, but he went much further in concluding that Switzerland once had an ice cover similar to that of Greenland today ? a vast sheet of ice originating in the higher Alps and extending over the alpine foreland to the summits of the Jura Mountains. Publication of this work led to the study of glacial phenomena in all parts of the world and to repudiation of the idea, widely accepted in the mid-1800s, that drift was the product of the great Noachian flood. After publication of this work, Agassiz visited the mountains of Scotland with William Buckland, where the two found similar evidence of past glaciation. They concluded that the mountainous areas of England, Wales, and Ireland were centres for the dispersion of ice and glacial debris; Agassiz remarked "that great sheets of ice, resembling those now existing in Greenland, once covered all the countries in which unstratified gravel (boulder drift) is found; that this gravel was in general produced by the trituration of the sheets of ice upon the subjacent surface, etc".
Agassiz moved to the United States in 1846 and became a professor of zoology and geology at Harvard, a position he occupied until his death in 1873. During his tenure at Harvard, he became an early advocate of continental glaciation in North America. He grew in fame, becoming one of the best-known scientists of his time.