then you shall tell them, Because the waters of the Jordan were cut off before the ark of the covenant of Yahweh; when it passed over the Jordan, the waters of the Jordan were cut off: and these stones shall be for a memorial to the children of Israel forever.
So Joshua [verse nine] set up twelve stones in the midst of Jordan, in the place where the feet of the priests that bare the ark of the covenant stood: they're there to this day ( Joshua 4:9 ).