Near Tuba City, Arizona there is an area of dinosaur footprints in sandstone. The ideal time to photograph them is either sunrise or sunset, but I was there in the middle of the day. To avoid the harsh, direct sunlight, I used the shade of my body to create diffused light. To increase the contrast between the impression in the stone and the surrounding surface, I poured some water it. That made the darkened footprint stand out perfectly.
To maintain complete depth of field from edge to edge, I stood directly over the sandstone so the back of the camera (i.e. the plane of the digital sensor) was paralle with the surface. My settings for this were 1/60, f/11, and 250 ISO. I used a 24 - 105mm lens set to 40mm.