5.2: Evidence of Moving Continents

Evidence of Moving Continents

The idea that the continents appear to have been joined based on their shapes is not new; in fact, this idea first appeared in the writings of Sir Francis Bacon Links to an external site. in 1620. The resulting hypothesis from this observation is rather straightforward: the shapes of the continents fit together because they were once connected and have since broken apart and moved. This hypothesis refers to a historical event and cannot be directly tested without a time machine (and we don’t have those yet). Therefore, geoscientists reframed the hypothesis by assuming the continents used to be connected and asking what other patterns we would expect to find.

This is exactly how turn of the century earth scientists, such as Alfred Wegener Links to an external site., addressed this important scientific question. Wegener compiled rock types, fossil occurrences, and environmental indicators within the rock record on different continents that appear to have been joined in the past, focusing mainly on Africa and South America; he found remarkable similarities across the continents! Other scientists followed suit and the scientific community was able to compile an extensive dataset that indicated that the continents were linked in the past in a supercontinent called Pangaea Links to an external site. (named by Wegener) and have shifted to their current position over time. Dating these rocks using both relative and absolute methods allowed scientists to better understand the rate of motion, which has assisted in trying to determine the mechanisms that drive plate tectonics.