Rapa Fortification (IMAGE) University of Oregon Caption Rising high on the island is the Tevaitau Fortification. The mountaintop was flattened, with evenly spaced layers carved along the way to the top. Researchers suspect that fortifications resulted as division grew among the island's growing population. Credit Photos courtesy of Douglas Kennett Usage Restrictions Media use only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.