Study the structure of the following excerpt from the article about tectonic plates called "Historical Perspective" from the U.S. Geological Survey. The belief that continents have not always been fixed in their present positions was suspected long before the 20th century; this notion was first suggested as early as 1596 by the Dutch map maker Abraham Ortelius in his work Thesaurus Geographicus. Ortelius suggested that the Americas were "torn away from Europe and Africa . . . by earthquakes and floods" and went on to say: "The vestiges of the rupture reveal themselves, if someone brings forward a map of the world and considers carefully the coasts of the three [continents]." Ortelius' idea surfaced again in the 19th century. However, it was not until 1912 that the idea of moving continents was seriously considered as a full-blown scientific theory--called Continental Drift--introduced in two articles published by a 32-year-old German meteorologist named Alfred Lothar Wegener. What words in this excerpt are transition tags that signal chronological order?