In 1837, Agassiz proposed that the Earth had been subjected to a past ice age. He presented the theory to the Helvetic Society that not only had ancient glaciers flowed outward from the Alps, but even larger glaciers had covered the plains and mountains of Europe, Asia, and North America, smothering the entire Northern Hemisphere in a prolonged ice age. In the same year, he was elected a foreign member of the Royal Swedish Academy of Sciences. Prior to this proposal, Goethe, de Saussure, Venetz, Jean de Charpentier, Karl Friedrich Schimper, and others had studied the glaciers of the Alps, and Goethe, Charpentier, and Schimper had even concluded that the erratic blocks of alpine rocks scattered over the slopes and summits of the Jura Mountains had been moved there by glaciers. These ideas attracted the attention of Agassiz, and he discussed them with Charpentier and Schimper, whom he accompanied on successive trips to the Alps. Agassiz even had a hut constructed upon one of the Aar Glaciers, which for a time he made his home, to investigate the structure and movements of the ice.