That 3 rd picture has a hoyo. Look through that from both sides of the rock. The next marker site will be viewable through that little "window". If you see ground in both directions, you will have a lot of walking to do to check out the areas. If the ground is seen in only ONE direction, and nothing but sky is seen in the OTHER direction, then that cuts down the search area. Sometimes the very SHAPE of the hole has clues such as a pointer that indicates what part of the ground in the "picture" to take a closer look.
There are thread subjects in this forum area concerning the hoyos and how to use them. Read them and study them, if you haven't already done so. Old Dog, dsty, rangler, and a few other folks are highly knowledgeable about them.