Q. There is a 5 mile long aqueduct next to Cajamarca (Peru) called Cumbe Mayo (in Quechua this means "thin river" because its width never exceeds 70 cm/28 inches): This pre-Incaic water channel precisely cut into stone as we cut pieces from the cake, is full of petroglyphs, maps, astronomical charts and stuff. As interesting as understanding who did it, when, who assisted them,etc, I'm learning why they did it because (nowadays) there's no lack of water where this piece of art directs the liquid!
A. I first get that this is man made in certain areas, but in others the geographic terrain was suitable for this project and intervention or modification was not needed. I realize the question says "pre-Incan" but I do see an Indian tribe building and working on this. I get an impression (I see the Indian tribe pointing to the sky) that ETs had some kind of influence on the building or knowledge of why they should have this "river." It it being shared that even though there is water at the destination, this river was built as a way to have a healthy and pure water supply. This water from the river was used for drinking and cooking, nothing else. Bathing, laundry, fishing and cleaning were done in the bodies of water that already existed. The ETs explained that need for fresh water to reduce disease and promote health. The Indian tribe constructed this to ensure their survival.
This river was highly protected. The Indians would keep it clean. It has such a feeling of purity that I even see them praying to or about it.
This river was adorned with drawings. I get that if the pictures could be deciphered they would tell a story of how this river gave and promoted life. This river was good luck and was very sacred to this tribe.
And that is all I have on this reading. Thanks you. Narrated reading available on YouTube.