There are several solstice markers in the park. This is the easiest to see. You can see the crack in the rock. Near the bottom on the right is a smaller rock that has petroglyph on it. The petroglyph that is a spiral on the darkest part of the rock indicates when the summer solstice is. When the sun shines through the crack in the large rock and shines on the spiral, about June 20, it is the summer solstice or the beginning of the summer season. Ancient peoples all over the world marked the time of the solstices. I always wonder how many years did they have to watch a place to see that the sun would shine at a certain point at that exact day. And why would they watch this certain rock? There is so much land that could mark a solstice or other important event, in such a similar way, that may have never been found even yet.