They’re being compared, for obvious reasons, to Peru’s equally mysterious Nazca Lines, such as those shown above.
(Wikimedia CC; click to enlarge.)
http://www.nytimes.com/2015/11/03/science/nasa-adds-to-evidence-of-mysterious-ancient-earthworks.html?rref=collection%2Fsectioncollection%2Fscience&_r=0
It seems that we don’t yet know and understand absolutely everything about the past.