Fisk Holbrook Day (1826-1903) was a physician and an amateur geologist in Wisconsin who developed an impressive collection of Silurian-age fossils.
He moved to Wauwatosa, Wisconsin, and lived there for 40 years, "and at one time was considered its most prominent citizen."
[2] [3] One of the primary places he collected was at the Schoonmaker Quarry, which professional geologist/paleontologist James Hall had recognized in 1862 as the first known fossil reef in North America.
[1] "Day supplied specimens and information to other professional geologists, including Fielding Bradford Meek (Smithsonian Institution), Charles Doolittle Walcott (future Director of the U.S. Geological Survey and Secretary of the Smithsonian Institution), E.O.
In addition to his interactions with professional scientists, Day corresponded and exchanged specimens with amateur naturalists around the country.