Located in an ancient flood channel, the Natural Bridge in Death Valley National Park looks more precarious than other arches you might see in the desert southwest.  Carved out of the same conglomerate that forms the sides of the narrow gorge, the bridge is riddled with large cracks and spans from the bulk of the south wall of the channel to a smaller pedestal on the north side.  The bridge is reached by a 15 minute gradual climb up the pebble and sand floor of the channel.