Neoproterozoic mafic dike exposed at Mount Moran, Teton Range, Wyoming. Based on paleomagnetism and ⁴⁰Ar/³⁹Ar geochronology, the dike is considered to be part of the 780 Ma Gunbarrel mafic magmatic event. At the top of Mount Moran, the dike is nonconformably overlain by the Cambrian Flathead Sandstone. (Photograph by Stephen S. Harlan)