I guess that geologists say that this is some kind of exfoliation, a form of mechanical weathering in which plates of rock are stripped from rock below. But why do we find so many examples at the Inca sites of very even and regular layers that are peeling off from the stoneblock? Why is the effect the same on the horizontal part and on the vertical part of the stone? Why is it always there where we also find the very smooth and even surfaces that according to Jesús Gamarra are vitrified?
Also according to him, the layer is peeling off because the surface was treated with heat. It caused the formation of a layer with a different chemical composition, glass like, and that is the reason that in time the layer looses the connection with the rock below it. There are definitely many examples to be found all over the inca sites. Another reason to believe that this is not a typical geological phenomenon, is the fact that it can be seen on many different kind of stones. See also the picture on the left where we see the reflection on a big part of the layer.
Some geologists seem to think that the shine is because of polishing and also that the layer peels off because of having been polished. The temperature explanation makes more sense to me, besides that inspection of the rocks and stones at the sites themselves made it clear that vitrification is for real. A chemical analysis of the layers of these rocks would certainly give more insights on how these megaliths were constructed. A pity that archaeologists normally miss the point and rapidly accept the polishing explanation.
For more on the vitrification of rocks, see here; Vitrified Stones
Do you want to come and see it and make your own opinion, join us on our August jounrey with the USOKS, see Tour Peru August 2014