The ruins of the prehistoric Bolivian city of Tiwanaku feature green andacite stones weighing up to 40 tons  These stones were quarried at Copacabana, which is across a lake and about 90 kilometers away  Archaeologists hypothesize that the stones were brought to Tiwanaku on reed boats
To show this was possible, experimenters transported a 9-ton stone from Copacabana to Tiwanaku using a reed boat built with locally available materials and techniques traditional to the area
whether green andacite stones quarried at the time Tiwanaku was inhabited were used at any sites near Copacabana