Trying to pull together some thoughts from this thread and the related “boulder floating” thread; there are obviously a lot of questions to be answered, but Paul’s link to the Nova experiments seems to provide a reasonable answer to the question of cutting the granite. Sand, which will be almost entirely quartz (Moh’s scale 7) should effectively abrade granite which, if I remember rightly, has an overall hardness of about 5 – 5.5, so alien intervention or that of an earlier, more advanced, civilisation can be replaced by the use of natural materials such as sand and water.
The remains of sea salt at 400ft above current water level will take a bit more explaining if we want to stick with the idea that the Egyptians built these structures. Even Eddy Pengelly’s time travellers would not explain that one. I suspect that Eddy would balk at Paul’s (hopefully, tongue in cheek) time travel scenario.
