Evidently this type of spiral holds some significance.
Looks like the Nazca spirals are still under research. According to this website, "While these lines remain an enigma, the new study has revealed that puquios - spiralling holes that sink into the ground- were part of a complex system used to irrigate crops in this desert land".
"These spiral structures formed a ventilation system that channeled wind to a network of underground canals used to irrigate crops and bring water where there were no springs or streams".
Thanks for the link! These puquios look a lot like dew ponds to me and I would say there is no mystery here. Water collects on them in the mornings and runs down into the centre, automatically feeding the canal system and ultimately the plants. It is an old technique, not used much any more, to get water where there is none. They don't want the average person knowing about this technique because they are trying to uphold the perception that water is a precious resource in short supply on planet earth. Only in this way will they continually be able to pump the prices up.