In 1891, at the 5th International Geological Congress in Washington DC, it was suggested that Switzerland should host the 1894 Congress. Since Switzerland had not issued an official invitation for the 6th International Geological Congress, the Swiss geologists accepted somewhat reluctantly. The general lectures still concerned problems of classification. The most interesting discussions had to do with the structure of the Alps. The conference took place at a time between the first recognition of nappes and the general acceptance of their existence. The proponents of the nappe concept (Bertrand, Schardt; later Suess and Lugeon; modified versions: Rothpletz, Golliez) and the autochthonists (Heim, Baltzer; essentially also Renevier and Schmidt) opposed each other fiercely, before the question was finally resolved at the turn of the century.