One of the factors that contributed to so many geoglyphs being undetected prior to the aid of satellites is their enormous size. According to leading geoglyph scientist Alceu Ranzi, his latest discoveries–five sets of geometric shapes, with circles, squares and lines–can measure more than a mile from one extreme to another.
You do not see them in field. There is a difference in the color of grass but is very thin. If there were no satellite images, there would be no possibility [of making these new discoveries.]
Because they’ve been so hard to find, the first geoglyphs weren’t discovered until the 1970s. Since then, scientists have been trying to piece together what significance they may have had to ancient Amazonians. What ever the purpose may have been, there’s one thing that is certain: the ancient civilizations of the rainforest were more numerous and sophisticated than previously imagined.