enigmatic51 -- My guess, and this is purely a guess, is that the heart/lightning bolt petroglyph indicates that you are on the trail, if the petroglyph is above the rock man. The lightning bolt could indicate that you are near the end of the trail. If the lightning bolt is straight up and down, I'd say you would want to directly face the petroglyph and proceed in that direction, if possible. If the lightning bolt is pointing left or right you would want to go in that direction. Other signs/symbols might not be on rocks; they could be carved into cacti, or in the form of stacked rocks, or in the form of rocks placed in patterns on the ground. I'm sure someone here on T-net can tell you exactly what the petroglyph means. I think you are on a trail to something.