The Denver fossil algae database were gathered from the inception of Denver Region in 1953 by Richard Rezak. His specialty was algae, carbonate platforms, and off-shore modern reefs. He developed a very useful litho-stratigraphic tool while studying Proterozoic algae and stromatolites in Glacier National Park. This lead to his studies of modern analogs in the Caribbean and South Seas. His catalogs were converted into digital form, Excel and Filemaker Pro database. The Catalog consist of 1001 fossil localities. His supplementary data has been added whenever possible - sources field map locality points, E&R files with enhanced faunal lists, as well as formal publications