The Map Collection holds a large collection of geologic maps, historic geologic folios, atlases, field guides, air photos of geologic features, and orthophoto maps. The collections focuses primarily on Southern California, but also contains a variety of locations in the United States. Of particular note, is the very large collection of Dibblee geologic maps and reports. These maps are known to even the most amateur students of the geology of California. Thomas Wilson Dibblee, Jr. was one of the most prolific field geologists in American history. Over a period of 60 years, he not only mapped over one fourth of the State of California, but in so doing, established his name as gold standard for geologic maps of California. Much like any time a brand name becomes known more than the actual item name, requests for these maps often have the “geologic” dropped out of them and are simply referred to as “Dibblee Maps”.