GALACTIC ENCOUNTERS, APOLLO OBJECTS AND ATLANTIS: A CATASTROPHICAL SCENARIO FOR DISCONTINUITIES IN HUMAN HISTORY Emilio SpedicatoUniversity of Bergamo Acknowledgements The author acknowledges stimulating discussions with Thor Heyerdahl (Colle Micheri, Liguria and Guimar, Tenerife), Laurence Dixon (University of Hertfordhshire), Victor Clube (Oxford University), Emmanuel Anati (Centro Camuno di Studi Preistorici), Zdenek Kukal (Central Geological Survey, Prague), Donald Patten (Seattle), Flavio Barbiero (Livorno), Antonino Del Popolo (Bergamo), Lia Mangolini (Milano), Graham Hancock (Leat Mill, Lifton) and Andrew Collins (Leigh on Sea). Third revised version. First version published in 1985 as Quaderno 85/3. First revised version published in 1990 as Quaderno 90/22...