RESTON, Va. — This weekend, the U.S. Geological Survey (USGS) celebrates the 140th birthday of President Herbert Hoover, who was the only USGS employee to hold office, but the second geologist to act as President, according to a press release.

President Hoover was a USGS geological assistant for three summers in the early 1890s, and his tenure at USGS was influenced by his Stanford University professor, John Casper Branner, who also was the president of Stanford’s Department of Geology and the state geologist of Arkansas, stated the release.

Branner influenced Hoover’s decision to switch his major from engineering to geology and in the summer of 1892, Hoover worked with Branner for the Arkansas State Survey in the Ozarks, continued the release.

During his time at USGS, Hoover mapped the eastern slope of California’s Sierra Nevada mountain range with renowned geologist, Waldemar Lindgren, noted the release.

You can find the entire USGS release here.