USGS Denver Library Photographic CollectionThe Photographic Collection is an archive of more than 500,000 still photographs, slides, glass plate slides, lantern slides, negatives, and sketches dating from the 1870s and taken by USGS scientists as part of their field studies. The images and photographers involved with this collection span a variety of styles, locations, and time periods. Subjects include earthquakes, volcanoes, geologic formations, minerals, historical mining operations, national parks, USGS portraits, and other photographs of historic and earth science events.