Suess published a comprehensive synthesis of his ideas between 1885 and 1901 titled "Das Antlitz der Erde" ("The Face of the Earth"), which was a popular textbook for many years. In volume two of this massive three-volume work, Suess set out his belief that across geologic time, the rise and fall of sea levels were mappable across the earth—that is, that the periods of ocean transgression and regression were correlateable from one continent to another. His theory was based upon glossopteris fern fossils occurring in South America, Africa, and India. His explanation was that the three lands were once connected in a supercontinent, which he named Gondwanaland. Again, this is not quite correct: Suess believed that the oceans flooded the spaces currently between those lands.