Sir John William Dawson, (born Oct. 30, 1820, Pictou, Nova Scotia [now in Canada]—died Nov. 20, 1899, Montreal, Que., Can.), Canadian geologist who made numerous contributions to paleobotany and extended the knowledge of Canadian geology.
During his term as superintendent of education for Nova Scotia (1850–53), Dawson studied the geology of all parts of the province, making a special investigation of the fossil forests of the coal-bearing strata. In the same year that he published the results of his studies in Acadian Geology (1855), he became professor of geology and principal of McGill University, Montreal. During the following 38 years he transformed McGill from an understaffed, insignificant school into a progressive university with a worldwide reputation. In addition, he maintained a rapid pace of scientific writing, averaging more than 10 papers a year, and he helped found the Montreal Normal School, serving as its principal for 13 years.
In 1859 he announced his discovery of the then-earliest-known land plant, Psilophyton, which he found in Devonian strata (dating from 408 to 360 million years ago). In Air Breathers of the Coal Period (1863) he described newly discovered fossil animals. Dawson was knighted in 1884.