In 1914 the office of chief inspector of mines was made a separate one, but Twelvetrees continued to act as government geologist and director of the geological survey of Tasmania until his death. He worked with energy and enthusiasm and his department grew in size and importance. He also interested himself in the Launceston Museum, which was extended so that the excellent geological survey collection of specimens could be housed. He died at Launceston after a short illness on 7 November 1919.
