Te Pito Te Henua, or Easter Island, by William J. Thompson, , at sacred-texts.com
In the rear of some of the best-preserved platforms are stones said to have been erected for sacrificial purposes. These altars consist of a single shaft, generally of vesicular lava, but in some cases cut from the material of which the images and crowns were, made. They range in height from 5 to 10 feet, squared to 3½ or 4 feet on each face, and stand in the center of a terrace paved with smooth bowlders. The sides and plinth were covered with figures sculptured in low relief, but are now too much weather-worn to be traced. These altars are said to have
been designed and used for human sacrifices, but of this a reasonable doubt may be expressed. The form is inconveniently adapted to the purpose and the stories differ in all respects from those used for the same purpose in the other islands. Evidences of fire on top of stones were plain enough, but no charred bones were found except those of recent date belonging to sheep and cattle.