[Fred Nerks]

http://www.photogrammetry.ethz.ch/research/3Dmodels/nasca.html

this site has several 3D images, the one above is my favourite, it looks as if the lines existed before the mountain was 'washed away'

[SunkenCiv]

I wonder if the Nazca lines weren't related to high-altitude agriculture -- analogous to the efforts of the Nabataeans (city of Petra) to capture runoff?