Dawson, Sir John William (1820-1899), was a Canadian geologist and educator. His major work was Acadian Geology (first published in 1855), a study of rock formations in Nova Scotia. The book vigorously opposed the theory of naturalist Louis Agassiz that a huge sheet of ice once covered large regions of the Northern Hemisphere. Dawson incorrectly believed that glaciers had covered only small areas of the earth.