United States Geological Survey

Day was with the U.S. Geological Survey from 1900 until 1907, when he became director of the Geophysical Laboratory of the Carnegie Institution of Washington, Washington, D.C.; he retired in 1936. He was vice president of the National Academy of Sciences (1933–1941) and president (1938) of the Geological Society…

…pioneer investigator of the western United States. His explorations and geologic studies of the Great Plains and Rocky Mountains helped lay the foundation of the U.S. Geological Survey.

In 1889 he joined the U.S. Geological Survey as an assistant paleontologist and was associated with the survey until his death.

…serve as president of the USGS and as a science adviser to the secretary of the interior.

…senior geologist (1924–35) with the U.S. Geological Survey. He conducted a number of important expeditions and named several dinosaur genera and species, including Ornitholestes (1903), Tyrannosaurus rex and Albertosaurus (1905), Pentaceratops (1923), and Velociraptor (1924). He introduced a highly successful instructional approach

…as an assistant with a U.S. Geological Survey party in Yellowstone Park and later in Montana. He joined the faculty of Yale University in 1892 and became professor of physical geology in 1897. In Quantitative Classification of Igneous Rocks (1903), Pirsson, along with the U.S. geologists Whitman Cross, Joseph Iddings,…

…served as director of the U.S. Geological Survey from 1881 to 1894. During his tenure he touched off controversy by advocating strict conservation of water resources in the developing states and territories of the arid West. “There is not enough water to irrigate all the lands,” he remarked at a…

…was a member of the U.S. Geological Survey from 1924 until 1960, after which he was a professor of geology and geophysics at the University of California at Los Angeles until he retired in 1969.