The first inhabitants arrived in the fourth to seventh centuries. The platforms were prior to the statues, which were carved after 1000 AD. After 1680, many believe there was a social collapse resulting in warfare and the end of carving. Many people believe the art stopped because of an ecological crisis.
The hardness of the surface of the statue is dense but the rock beneath is not and can be shaped and softened with water. The tools used were hard picks of stone.
In the book, The Statues That Walked, authors Terry Hunt and Carl Lipo say that “…large carved holes in the bedrock near the crater’s summit are likely evidence of giant palm logs fixed into the cliff as part of massive pulleys" to maneuver at least some of the moai. The first experiments done by Thor Heyerdahl showed the massive loads were moved horizontally but that theory doesn’t fit in with the archaeological record.
After much observation and careful trials, Lipo and Hunt believe the upright statues were moved in a vertical posture by an intricate method of securing them with ropes and rocking them in choreography of men with pulleys, in order to make them walk.
The other idea is they were placed in the prone position (horizontally) on a wood platform of rolling timber and pushed or pulled. The island is quite barren but evidence of previous forestation of palms can be seen in the roots carved into rock as they grew. Also the giant palm trees with nuts cultivated back then may have been feasted on (and the subsequent seeds) by invasive rats. Lacking predators for the seed loving vermin, the devastation of the palms was complete.
In 1995, UNESCO (United Nations Educational, Scientific and Cultural Organization) declared Rapa Nui National Park. That means it is the scene of a permanent