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.

Accokeek, "at the edge of the hill" in Algonquin, is a census-designated place (CDP) located in Prince George's County, Maryland, United States. The CDP is located on the Potomac River, borders Charles County and is approximately 17 miles from Washington. It is a part of the Washington metropolitan area. The population of the CDP, as of the 2020 United States Census was 13,927.