Geologist John Prentiss Thomson was born July 12, 1903 in Norfolk, Virginia. He graduated from Ellensburg, Washington, High School in 1923, attended the State Normal School at Ellensburg the following year, then went on to the State College of Washington (Washington State University, Pullman) where he earned a bachelor of science in geology in 1928 and a master of science in 1932. He was a member of the National Guard from 1921 to 1924. His father, J.N.O. Thomson, was a jeweler and prominent citizen of Ellensburg.

Thomson began his career in 1930 as a transitman with Land Cruise of Kittitas County, Washington. In 1931, he was hired by the Washington Geological Survey and in 1932, became a geologist with the Na-Cal-Sun Mineral Springs Company of Eugene, Oregon. In 1933, he was an appraiser for the Federal Land Bank’s Yakima Division, and then in 1934, was a resident engineer with the Mineral Survey of Washington. He joined the U.S. Department of Agriculture’s Soil Conservation Service later in 1934 as an engineering assistant. He was promoted to project manager for Western Idaho and Oregon; regional training officer; and soils surveyor for Washington, Oregon, and Idaho. He conducted surveys and investigations of soils, land use, and dam sites, and did geologic mapping and groundwater surveys in Alaska, Washington, Idaho, Oregon, and South Dakota.

In 1954, Thomson became a member of the first Washington State University-Pakistan Exchange Program and with two others established the Department of Geology and Mining at the University of the Punjab, Lahore, West Pakistan. He taught geology and mineralogy and reported on mineral deposits for the American Consulate General in the Northwestern Frontier and Punjab Provinces.

Returning to the United States in 1956, Thomson joined the U.S. Bureau of Land Management in Spokane, Washington, as a land examiner until 1964. In this capacity he engaged in state mineral exams, mineral resource surveys, mining claim validity determinations, and did geological reporting on the Colville Indian Reservation. In 1966, he was employed as a geologist for the BLM Boundary Dam Project in Pend Oreille County, Washington. He later became an independent consulting geologist on topics such as ground water geology and small mine examination in Alaska and the northwestern states. Over the course of his career he authored several magazine and newspaper articles related to geology.

Thomson married Virginia Elofson in 1934 and had one daughter, Janet. He died in 1984.