The second author is Roland Wernli. He is a former professor in the Department of
EarthSciences at the University de Geneve You can get his e-mail address here under former professors: http://cms.unige.ch/sciences/terre/people/people.php. Why not ask him if he can send you a reprint? Alternatively, you can purchase a reprint from the journal: http://www.unige.ch/sphn/Publications/ArchivesSciences/Archives.html
The journal indicates that older articles can be purchased by contacting the following institution:
Musée d'Histoire Naturelle, Case postale 6434, CH-1211, Genève 6, Suisse
The journal website lists a Ms. Catherine de Jong as the secretary at the Musée d'Histoire Naturelle. They giver her e-mail address. Perhaps she can help? Good luck.