Albert Charles Peale (1849-1913), the great-grandson of Charles Willson Peale (1741-1827), was a geologist for the United States Geological Survey (USGS) and its predecessor agency, a member of the Ferdinand Hayden expeditions that explored and mapped the western United States, an author in geology, mineralogy, and paleobotany, and an aide at the United States National Museum (today the Smithsonian Institution's National Museum of Natural History). Edwin Roger Kirk (1884-1955) corresponded with Frank Springer about crinoids; assisted Edward Ulrich in studying sediments of the Appalachians; surveyed the Rocky Mountains, the Great Basin, and southeastern Alaska as a USGS paleontologist; and collected the papers of Peale and other geologists. Peale's correspondence (1868-1912, bulk 1870s-80s) relate to various federal geological expeditions. Letters between Peale and William Rush Taggart, the largest single portion of the series, focus on matters of congressional funding. Kirk's series (1900-09) contains the correspondence of Kirk and other geologists; most frequent are letters from Frank Springer to Kirk relating to rock formations. The collection also contains several diaries and sketchbooks from Peale (bulk 1872-77), including those kept during the Hayden expeditions, correspondence relating to the Geological Survey of Kentucky (1888-1893), and miscellaneous letters and memorabilia (c. 1820s-1940s), often relating to the Peale family.

A miscellaneous collection of letters written by naturalist Louis Jean Rodolph Agassiz concerning a wide range of topics: natural history and naturalists, geology, mineralogy, fossils, publications, expeditions, and the Museum of Comparative Zoology at Harvard, which he founded.