As a subject matter expert in the field of geology and earth sciences, I have spent considerable time studying the various theories and evidence that explain the geological phenomena on our planet. One of the most intriguing and well-known hypotheses is the concept of continental drift, which has been further developed into the theory of plate tectonics. Within this framework, the term "jigsaw fit" often comes up, particularly in discussions about the historical fit of the continents before they drifted to their current positions.
Jigsaw Fit refers to the observation that the coastlines of certain continents appear to fit together like pieces of a jigsaw puzzle when the current continental positions are adjusted for the effects of continental drift. This concept was a significant part of the early evidence that led to the development of the continental drift hypothesis.
The idea was popularized by the German geophysicist and meteorologist Alfred Wegener, who, in 1912, proposed the theory of continental drift. Wegener noticed that the protruding coastline of South America and the indented coastline of Africa seemed to fit together remarkably well. This observation was not just a simple curiosity; it was a clue that hinted at a deeper geological connection between the continents.
The similarity in outline of the coastlines of eastern South America and West Africa is indeed striking. When you look at a map and align the two continents, it's as if they were once part of a single landmass. This visual evidence was one of the first pieces of the puzzle that suggested the continents were not static but had moved apart over time.
The best fit is obtained when the coastlines are matched at a depth of approximately 1,000 meters below the current sea level. This depth is significant because it suggests that the continents were once joined at a time when sea levels were much lower, possibly during a past ice age when water was locked up in glaciers and ice sheets. The fit at this depth also implies that the continental masses have not simply drifted apart on a flat surface but have been influenced by subduction and other tectonic processes that reshape the Earth's crust.
The jigsaw fit is not just a superficial match of coastlines; it is supported by a variety of geological, biological, and paleoclimatological evidence. For instance, the same rock formations are found on opposite sides of the Atlantic, and fossils of certain species that could not cross vast oceans are found in what are now widely separated locations. These are strong indicators that the continents were once connected.
Furthermore, the fit is not limited to just South America and Africa. Similar fits can be observed with other continents, suggesting a global reassembly of the Earth's landmasses. The concept of the jigsaw fit has been instrumental in advancing our understanding of the dynamic nature of the Earth's surface and the forces that drive the movement of the continents.
In conclusion, the jigsaw fit is a compelling piece of evidence that has contributed to our current understanding of plate tectonics and the historical movement of continents. It is a testament to the power of observation and the importance of integrating various lines of evidence to form a comprehensive picture of our planet's geological history.

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Jigsaw Fit. The similarity in outline of the coastlines of eastern South America and West Africa had been noted for some time. The best fit is obtained if the coastlines are matched at a depth of 1,000 metres below current sea level.read more >>