John Haun is an influential petroleum geologist with careers both as an independent explorationist and professor. In the 1950s, with partner Jim Barlow, he explored extensively the Rocky Mountain basins. Together Barlow and Haun produced regional basin maps still widely used by geologists and companies today. As a professor at Colorado School of Mines, John taught petroleum geology to countless students in geology, geophysics, and petroleum engineering. He co-authored and co-edited the influential text Subsurface Geology in Petroleum Exploration used by two generations of geologists. He is currently Professor Emeritus of Stratigraphy and Petroleum Geology at Colorado School of Mines. While President of the AAPG, John founded the AAPG Explorer. He is a former editor of the AAPG Bulletin and was awarded the Sidney Powers Memorial Award, AAPG’s highest honor.