What proof do you have that i'm incorrect and how do you know the stone was from elsewhere? i believe you don't have any real evidence at all and can't know where the stone is from originally (it's all at the same site anyway)!!! These Propped stones exist because the softer stone/sand has eroded away (sometimes "maybe" with man's help moving the softer rock/sand) over 1000's if not 1000000's of years by the elements, leaving only (often small) harder stones supporting massive stones, because it often looks strange people think that other people must have done it, they normally haven't as it's a totally natural process, i suggest you study geology a bit more, hopefully you'll then see the light, you've decided your right and seem to want to run with it, exactly like your doing with alignments - There's that many ancient site's down here that you'll always find alignments, it's another thing proving they were meant or known about by the builders of these (often from totally different times) sites.
Something is not right. This message is just to keep things from messing up down the road