Alexander became the Geologist to the Government of Singapore in 1949, surveying the island and publishing a report in 1950 which included the first geological map of Singapore.[18] For this work, she is credited with having produced one of the most comprehensive papers on the general geology of Singapore.[19] Alexander's main task was to assess the island's quantities of granite and other useful stone, and she concluded that granite resources should last for 500 years.[20] Alexander was also responsible for introducing the name "Murai Schist" to refer to a part of the Jurong Formation, and created the first documented collection of fossils in the area of the Ayer Chawan Facies.[19]