Dinosaurs once stomped across the Yukon, leaving tracks in mud that were buried in more mud and hardened to stone. Some may have been turned on end or turned over by mountain building; others were split apart and turned over by humans looking for dinosaur tracks and putting them in museums. The light was shining in from the upper right, as indicated, making lighter-looking and darker-looking places depending on whether they were facing the light or in shadow; we have indicated a shadow of the human glove and of the dinosaur track to help guide your eye. Are you looking at the side that was down when the sediment was soft, or the side that was up?