Mount Pennell is an 11,413-foot peak in Utah’s Henry Mountains, east of Capitol Reef National Park, where wooded upper slopes and canyon-cut flanks rise sharply from a dry, sparsely settled desert landscape. Known earlier to the Paiute as Un-chu'-ka-ret, it later became part of the nineteenth-century exploration and survey of the Henry Mountains associated with John Wesley Powell. The mountain took its present name from Joseph Pennell, while nearby Mount Ellen was named by Almon Harris Thompson. Mount Pennell is also linked to a major advance in geology: Grove Karl Gilbert’s 1875-1876 study of the Henry Mountains led to his 1879 introduction of the term laccolith, helping explain igneous mountain building.