Denver Harper has a background in both geology and mining engineering. Drawing upon his experience working in an underground coal mine, he began his career at the Indiana Geological Survey by mapping coal beds and investigations of mining geology. He subsequently became involved in a series of coal-mine-reclamation projects and investigations of coal-bed hydrology, including the potential use of mine pools for geothermal ground-source heat pumps. He has served as the project director or principal investigator for more than three dozen projects, many of which have involved the application of GIS-based methods. He has been involved in developing much of the content for the IndianaMap Viewer, an interactive online map that is widely used by consultants, government agencies, academia, and the general public.