Name	Known for
Corey Johnson Narrator (voice) Narrator (voice) See fewer	Morbius (2022)
Hank Heasler Self - Park Ranger / Geologist, Yellowstone National Park (as Dr. Hank Heasler) Self - Park Ranger / Geologist, Yellowstone National Park (as Dr. Hank Heasler) See fewer	Yellowstone: America's First National Park (2006)
Jake Lowenstern Self - Yellowstone Volcano Observatory, U.S. Geological Survey (as Dr. Jake Lowenstern) Self - Yellowstone Volcano Observatory, U.S. Geological Survey (as Dr. Jake Lowenstern) See fewer	Science Friction (2022)
Lisa A. Morgan Self - Geologist, U.S. Geological Survey (as Dr. Lisa A. Morgan) Self - Geologist, U.S. Geological Survey (as Dr. Lisa A. Morgan) See fewer	How the Earth Was Made (2009)
Henrietta Cathey Self - Geologist, University of Utah (as Dr. Henrietta Cathey) Self - Geologist, University of Utah (as Dr. Henrietta Cathey) See fewer	How the Earth Was Made (2009)
Barbara Nash Self - Geologist, University of Utah (as Dr. Barbara Nash) Self - Geologist, University of Utah (as Dr. Barbara Nash) See fewer	How the Earth Was Made (2009)
Cheryl Jaworowski Self - Park Ranger / Geologist, Yellowstone National Park (as Dr. Cheryl Jaworowski) Self - Park Ranger / Geologist, Yellowstone National Park (as Dr. Cheryl Jaworowski) See fewer	How the Earth Was Made (2009)
Robert Smith Self - Geologist, University of Utah (as Dr. Robert Smith) Self - Geologist, University of Utah (as Dr. Robert Smith) See fewer	Nova (1974)
Jim Bridger Self - Mountain Man (archive footage) Self - Mountain Man (archive footage) See fewer	Sex at Six (2001)
Robert Christiansen Self - Geophysicist (archive footage) Self - Geophysicist (archive footage) See fewer	Berlin - den permanente krise (1961)
William Clark Self - Explorer (archive footage) Self - Explorer (archive footage) See fewer	The Complete History of U.S. Wars 1700-2004 (2004)
John Colter Self - Mountain Man (archive footage) Self - Mountain Man (archive footage) See fewer
Meriwether Lewis Self - Explorer (archive footage) Self - Explorer (archive footage) See fewer