Coleman joined the department of geology and natural history at Victoria College in 1882 as a Professor. From 1891 to 1901, he was a Professor of Geology at the School of Practical Science in Toronto. From 1893 to 1909, he was a geologist at the Bureau of Mines of the Government of Ontario. From 1901 to 1922, he was a Professor of Geology at the University of Toronto and was Dean of the Faculty of Arts from 1919 to 1922. From 1931 to 1934, he was a geologist with the Department of Mines of the Government of Ontario.
In 1898, Coleman lead a field expedition with the intent of surveying resources, along with the Geologist George Mercer Dawson and the famed Anarchist, Peter Kropotkin. Kropotkin gave his credit to Coleman, writing he was "well acquainted with the mining region of Central Canada."[2]
In 1907, Coleman inferred a "lower Huronian ice age"[3][4] from analysis of a geological formation near Lake Huron.
The Last Million Years (1941) Edited by George F. Kay
He achieved the first ascent of Castle Mountain in 1884, and in 1907, he was the first white man to attempt to climb Mount Robson. He made a total of eight exploratory trips to the Canadian Rockies, wholly four of them looking for the mythical giants of Hooker and Brown.
Coleman was awarded the Penrose Medal of The Geological Society of America in 1936.[6]
His younger half-sister was poet Helena Coleman; the two shared a home in Toronto for much of their adult lives.
Lake Coleman, a lake with a higher water level, in the same basin as Lake Ontario, is named in Coleman's memory.[8] The lake, like Lake Iroquois and Lake Scarborough, is a product of the melting and drainage, of the Laurentide Ice Sheet.
^Fairchild, Herman LeRoy, 1932, The Geological Society of America 1888-1930, a Chapter in Earth Science History: New York, The Geological Society of America, 232 p.
^Eckel, Edwin, 1982, GSA Memoir 155, The Geological Society of America — Life History of a Learned Society: Boulder, Colorado, Geological Society of America Memoir 155, 168 p., ISBN0-8137-1155-X.
^Place-names of Alberta. Ottawa: Geographic Board of Canada. 1928. p. 36. Archived from the original on September 29, 2018. Retrieved May 23, 2019.