Private collection of Richard W. Gadd Joseph Paxson Iddings (1857-1920) was a petrologist who specialized in igneous rocks. He worked for the United States Geological Survey (1880-1892) and was a professor of petrology at the University of Chicago (1892-1908). He was a scientific traveler and writer (1908-1920). Iddings spent seven field seasons, 1883-1890, exploring and mapping the geology of Yellowstone.
