Beagle, thank you for starting this thread. Looking forward to where it goes/leads!
Visited Tiwanuku about 8 years ago, and there are definately things yet to be explained about this place.
Currently re-reading Hancock, and was reminded about the theory regarding Lake Titticaca's level being much HIGHER when Tiwinaku active. (There will always be the question by whom and when first, to be dealt with later in this thread I'm sure)
Upon visiting the town of Copacabana, the port/resort with nearest access to the Islands of the Sun and Moon. (also interesting megalithic observatory above town) There is an Incan/PreIncan road that "dissappears" into the lake at a steady and predictable angle, that would indicate that the Lake level has also been LOWER in its past.
The Island of the Sun has a small Archaeological museum/hut that has a stone coffer with a card stating it was retreived by divers from otherwise undocumented underwater ruins. I hear diving at 12,000ft above sea level can be tricky.
Besides being one of the most beautiful spots on the planet, it seems that there has seen some heavy geological lifting and heaving going on not so long ago in the Halocene +-. (Charles Hapgood anyone?) Also if my memory serves, there is no undue salinity in the water that might acompany a massive evaporation or possible sea origins.
It so far has been hard to find any definitve Geological chronolgy for the region, just alot of speculation and "camps". Any Geologist among us?
As for the terraces and raised fields, they are everywhere and easily discernable from the ground. Appearing and first look to be more related to the contours of the terrain, drainage and economy of effort rather than some grand design.
Recent field studies have shown the terracing continues to be a very efficient and sophisticated "lost" heritage of agriculture that is highly adapted to successful farming in an otherwise pretty inhospitable landscape......and the Google views does make one think again and perhaps outside the box.
Bauer and Stanish's "Ritual and Pilgramage in the Ancient Andes" has some excellent images of the intense terracing of the region as seen from the ground.
Will need to reread the Pre-Incan Chapter, will report back.
Also pictures from trip that unfortunately was pre-digital for me. Will do my best.
Its more complicated than it seems.