The fourth member of the group, a teenage warrior called Noisy Walking, was honored with a headstone in 1999. A cairn of piled stones left by his friends and family helped identify the spot where Noisy Walking was mortally wounded. It's not far from where the three new markers were placed. ....
...Cairns, along with Sioux and Cheyenne accounts written down after the battle, help determine where warrior markers should be placed. No cairns have been found yet
Note cairns related to death but not functioning as graves - PWAX