Final answer:
Alfred Wegener explained ancient glaciers and tropical swamps found in unexpected places through his theory of continental drift and the former existence of a supercontinent, Pangaea. Continental drift describes how continents once connected later separated, moving to their present locations, which explains the paleoclimatic evidence across various continents.
Step-by-step explanation:
Alfred Wegener explained the existence of glaciers in southern landmasses, such as South America, Africa, India, and Australia, as well as evidence of lush tropical swamps in areas that are now arid or cold, like North America, Europe, and Siberia, through his theory of continental drift and the concept of a supercontinent called Pangaea. According to Wegener, the continents we see today were once a single, large landmass that slowly drifted apart over millions of years. This once-connected world could account for similar fossil records and climate evidence across widely separated continents.
Wegener proposed that areas now at or near the poles, like parts of the southern continents, were once closer to the equator, allowing for conditions to support extensive glacial formation. Similarly, regions now in temperate zones could have experienced tropical climates, explaining ancient coal beds originating from lush swamps in the past. Continental drift provided a context in which such climatic and geographical discrepancies could be coherently explained.
Although he provided comprehensive evidence such as the fit of continents, matching fossils, and similar mountain ranges, Wegener was challenged due to the lack of a mechanism for this drift. It would be many years later that the theory of plate tectonics would provide the necessary scientific backing to explain the movement of continents.