I first read about Nazca lines in one of Erich von Daniken’s books. Now while doing the research for this post, I also found out that there is a thoery these lines might have been a map of underground irrigation systems.
This excellent website by Emma Johnson gives a detailed analysis – happy reading.
Johnson, Emma. 2007. The ‘Mysterious’ Nazca Lines. PARA Web Bibliography B-01. http://pseudoarchaeology.org/b01-johnson.html
Image Credit – http://en.wikipedia.org/wiki/File:Nazca_monkey.jpg