Aerial view showing faults associated with the northeastern side of the Yellowstone caldera. The view is looking south. Mirror Lake fills a depression (sag pond) formed by uneven settling of the ground along one of the faults. The low area between the large fault scarp in the sunlight and the next fault scarp to the right is a graben- a depression between two oppositely facing faults. The snow-covered Absaroka Mountains are visible in the far distance; Yellowstone Lake is visible in the upper right of the photo. Access to this remote part of Yellowstone National Park requires special permission.