The Heart Mountain Detachment Fault: A Critical Reappraisal

About the Book

The Heart Mountain Detachment Fault (HMDF) is an immense geologic structure in northwest Wyoming that, as defined prior to this study, extends from just inside the northeast entrance of Yellowstone National Park to areas southwest and northeast of Cody, WY. This enigmatic structure has puzzled geologists for more than 100 years. The consensus is that a massive slab of limestones and dolomites 320-485 million years old broke away from an outcrop near Silver Gate, MT about 49 million years ago and slid nearly 75 miles to the southeast at speeds of nearly 100 mph to more than 700 mph and broke up into several giant blocks up to five miles in diameter. Heart Mountain, north of Cody, WY, the namesake for this displacement, is where some of its geologic relationships were first recognized over 125 years ago.

Our research demonstrates that all of the geologic features attributed to the single event HMDF are instead the result of two geologic events separated in time by more than 47 million years. The first we term the Shoshone/Sunlight/Abiathar Detachment Fault (SSADF) that occurred ~49.5 million years ago, and the second we call the Heart Mountain/McCullough Peaks Sturzstrom (HMMPS) that occurred ~2.08 million years ago. A sturzstrom is a huge landslide that travels a great horizontal distance. Both massive displacements were instigated by violent tectonic processes. The SSADF was triggered by a powerful megathrust earthquake initiated by plate tectonic movements and followed by extensive volcanism, whereas the HMMPS was caused by a gigantic super eruption of a volcano in what is present-day Yellowstone National Park.

About the Author

Albert Warner is a petroleum geologist who received his B. Sci. (1965) and M. Sci. (1968) in geology at Iowa State University, and his Ph. D. in geology at the University of Iowa (1978). His professional career began in 1968 with Shell Oil Company in the Permian and Palo Duro Basins of Texas and New Mexico followed by 3 years prospecting in the Appalachian Basin for Columbia Gas Transmission Corporation. After spending 4 years from 1973-1977 earning his Ph. D. he returned to the petroleum industry in Oklahoma City where he developed drilling prospects in the Pennsylvanian sandstones of the Anadarko Basin for a number of companies including Gulf Oil Corporation, Slawson Oil, and Chesapeake Energy as well as an independent consulting geologist ultimately finding nearly 300 million barrels of oil equivalent. Additionally, he began a basin wide study of the principal producing Pennsylvanian sandstone reservoirs in the Anadarko Basin that has continued for 4 decades. As a member of the AAPG he has twice presented papers at annual regional meetings. Al is preparing a photoglossary of the Heart Mountain complex, a subject that has interested him for more than 50 years. awarner43@gmail.com Thomas Bown is a geologist/paleontologist who received his B. Sci. in geology at Iowa State University in 1968 and his Ph.D. in Geology at the University of Wyoming in 1977. He has accomplished geologic field studies in Wyoming’s Bighorn Basin for 60 years, in Egypt (22 seasons), Argentina (12 seasons), the UAE (3 seasons), Ethiopia (3 seasons), and in 6 other foreign countries. While working for Yale’s Peabody Museum in 1969, he and two others drove a field vehicle from India to Libya. At the U.S. Geological Survey and as a consulting geologist he contributed over 270 scientific publications and more than 100 technical site reports on topics as diverse as sedimentology, fossil mammals and trace fossils, paleosols, ground water resources, taphonomy, the world’s oldest paved road, the world’s oldest cattle kraals, and the Enos Creek/Owl Creek Debris-avalanche. He was the primary consultant on Britain’s Channel 4 documentary on The Lost Army of King Cambyses, and he published an historical novel, The Efreet, on the latter topic. Awards include the Outstanding Paper Award (SEPM), The Meritorious Service Award (U.S. Department of the Interior), The Morris F. Skinner Award (Society of Vertebrate Paleontology), The Distinguished Alumnus Award (Iowa State University), and a cash award from the United Arab Emirates for Outstanding Contributions to their Groundwater Research Program. kanprimate@aol.com Mark Mathison is a geologist/paleontologist/geomorphologist/stable isotope geochemist who received his B. Sci. in geology at Iowa State University in 1995 and his M.S. In geology also at Iowa State University in 2000. He has accomplished geologic field studies in Wyoming’s Bighorn Basin for 25 years, in Egypt (12 years), Norway (3 seasons), Sweden (2 seasons), Ethiopia, Mongolia, and in 5 other foreign countries. His work in Ethiopia resulted in the discovery of a new species of fossil fox (Vulpes mathisoni) that he had the honor to have named after him. 24 of the 25 years of work in Wyoming’s Bighorn Basin also included lecturing and managing Iowa State University’s geology field station near Shell, WY. Hundreds of field geologists were produced during this time. He was part of two influential papers; one on glacier slip and seismicity induced by surface melt, and a second on basal anthropoid primates from Egypt and the antiquity of Africa’s higher primate radiation. Mark is a commercial drone pilot and uses this skill to assist in geological research and to detect fossils by ultraviolet fluorescence by drone. With his technical skills he has developed wireless sensors to detect slip at the base of glaciers and has helped develop other automated sensors for use in geological fieldwork. mathison@iastate.edu