 But they're completely covered and overgrown by trees and these typical African umbrella-shaped trees and tall grass. And you don't see them from the air. You can't see them on Google Earth, because they're completely covered by the vegetation that has grown out of the stone circles and around them. So the question is, when these stone circles were built, or the suggestion is, rather, when they were built, the climate must have been the same. The vegetation must have been very different from what it is today.