“And the children of Israel did that.” One of the themes of the early part of Joshua was the people’s obedience to Joshua, who himself obeyed Yahweh. The act of setting up the stones from the Jordan is ascribed to “the children of Israel” even though only the 12 men actually carried and set up the stones because the men acted on behalf of the whole nation. In Joshua 4:9, “Joshua” is said to have set up the stones because he was causing and overseeing the whole event. There is no record of what happened to these stones, but the pile would likely have been dismantled by the enemies of Israel during the time of the captivities of Israel in the period of the Judges, or perhaps even later during Israel’s subjugation by Assyria, Babylon, Persia, etc. In any case, the pile is not there now.