Coleman retired from the University of Toronto and the Directorship of the Royal Ontario Museum of Geology in 1922. This left him free to investigate ancient and modern glaciers all over the world.
Coleman travelled throughout the United States for professional conferences as well as geological field work. He visited many of the major American mountain ranges including: the American Cordillera Mountains (Washington, Oregon and California); the Sierra Nevada Mountains (California and Nevada); Yellowstone National Park (Wyoming, Montana and Idaho); and the Appalachian Mountains (eastern United States). Pleistocene glaciation had extended in Northern Europe as far south as Berlin and London and covered an area of two million square miles. Coleman also visited such countries as India, Australia, Brazil, Argentina, Scandinavia, Bolivia, New Zealand, South Africa and Uruguay. In his final years he made two expeditions to the Andes in Colombia, to mountains in Southern Mexico and to two mountains in Central America. He planned to climb 'his' mountain, 'Mount Coleman' in the Albertan Rockies, and had also prepared a trip to British Guiana, but death intervened.
Coleman collected specimen of all the early glacial materials he encountered and many geologists sent and gave him representative samples from their finds. Coleman presented these samples to the Royal Ontario Museum, and they make up one of the leading collections of glacial materials in the world.