Here's the actual paper at PNAS, including a section discussing why they don't think it was natural processes.
Massive in length, but not in height. Fairly common globally, actually: done to funnel herd animals into a killing zone, and to provide built-in concealment for the hunters.
They sure chose a terrible image for the article: makes it look like a heap of stones, not a nearly 1 km long, well, wall:
I highly recommend people skim the discussion section of the paper- lays out things better than the brief article (and acknowledges the possibility of natural or more recent human creation, while arguing against both).