Halls Creek Overlook, located 3 miles down a rough unsurfaced road from the main Burr Trail, offers a superb view of the eastern edge of the Waterpocket Fold that makes up much of Capitol Reef National Park.  Directly across from the overlook, the Brimhall Natural Bridge is a double arch cut into the Navajo sandstone.  A strike valley separates the overlook from the fold.  Strike valleys form in sedimentary rock when softer layers erode between harder layers and the whole body of rock has been moved into a more vertical orientation - like standing plywood on its edge.  The red Entrada and white Navajo sandstone formations "leaning" to the west in the image mark the hard edge of the sedimentary block that eroded to form the valley.