 Tierney graduated from Iowa State College in Ames in 1961 with a bachelor's degree in entomology and worked for many years (1958–71) for the U.S. Forest Service in several western states and Alaska.Tierney has written widely on a variety of esoteric topics, such as the legends concerning Mount Shasta and Amne Machin.Well versed in Meso-American archaeology, during his time working for the Forest Service he spent four winters in Mexico, Central and South America visiting ancient Amerind ruins, (1962–66) photographing many of the most remote mountain and jungle sites—a background he uses in his later Cthulhu Mythos novel "The House of the Toad" (1993).