Jean-Pierre Protzen proved the Verrills wrong. He went to Cuzco and showed how river rocks could be used as hammers to pound stones into a simple rectangular shape.  It is worth noting that he was not able to come close to producing the complex curves of the cyclopean stones of Sacsahuaman.

"It appears that the Inca technique of fitting the blocks together was based largely on trial and error. It is a laborious method, particularly if one considers the size of some of the huge stones at Sacsahuaman or Ollantaytambo. What should be kept in mind, however, is that time and labor power were probably of little concern to the Incas, who did not have a European notion of time and had plenty of tribute labor from conquered peoples at their disposal."

Jean-Pierre Protzen ---Scientific American ---Feb. 1986