Sorry but humans dragging a block of stone through wet sand is going to have almost zero impact on its surface area, especially over the short distances describ

Sorry but humans dragging a block of stone through wet sand is going to have almost zero impact on its surface area, especially over the short distances described in the article. The forces needed to significantly erode the stone would be huge, and are inconceivable given the low friction between the block and the wet sand. Not that it matters, because the article is about dragging the blocks through wet sand on sleds - did you even read that?