In the Peruvian desert or Nasca region of the southern coast, geometric and geomorphic patterns created by the removal of surface stones to reveal the pale earth beneath. The lines were made by clearing the surface of small red/brown stones and exposing the lighter-colored soil underneath. The straight lines radiate to points in small hills and suggest a ceremonial function. The straight lines date to the Early Intermediate as well as to later periods. Maria Reiche, a researcher, believes that the figures represent constellations and the straight lines have astronomical significance. Others believe the lines pointed toward sacred places. The Nasca lines are virtually indecipherable from ground level, but are plainly visible from the air. The lines have been preserved by the extreme dryness of the climate of the region.