Henry Gardiner Ferguson was an American geologist with the United States Geological Survey (USGS). He worked primarily in Nevada and was a pioneer in the geology of the central Great Basin, producing many publications, including multiple USGS geological maps of central Nevada. Ferguson was a lifelong friend and colleague of Levi Noble, a mentor to Ralph Roberts, and worked extensively with Siemon Muller. Along with his wife Alice Ferguson, he helped found the Moyaone Reserve community in Accokeek, Maryland.

Levi Fatzinger Noble was an American geologist. His entire career was spent as a member of the United States Geological Survey (USGS). Noble is largely known for his work in the American southwest, particularly as a pioneer geologist in the Death Valley region.