Not sure if this will happily link directly without a referer but here goes: https://www.tandfonline.com/na101/home/literatum/publisher/tandf/journals/content/

Not sure if this will happily link directly without a referer but here goes: https://www.tandfonline.com/na101/home/literatum/publisher/tandf/journals/content/tejr20/2019/tejr20.v052.sup01/22797254.2018.1537684/20190322/images/medium/tejr_a_1537684_f0011_oc.jpg https://www.tandfonline.com/na101/home/literatum/publisher/t... The funnel shape of the ramp appears very deliberate, and not the kind of thing you'd naturally arrive at digging in sandy soil. The agressive slope towards the botttom would be especially frustrating. If the ground is very loose and wants to crumble and cave in like sand, getting the steep part of the ramp to hold its shape all these years required a lot of deliberate effort. At first I thought maybe it was just a spiral ramp for the laborers, since there's a lot of material to remove manually making such holes in general. But that agressive slope towards the end is not doing them any favors. It really does appear to be engineered with fluids in mind.