It has been theorized that all of the modern continents on Earth were once part of a single continent. What scientific evidence is used to support this theory?

1 Answer
Jun 18, 2016

Multiple sources biologically and geologically.

Explanation:

I will just briefly list the ones I know, if I miss some hopefully someone will fill in the blanks.

Biologically speaking, there are similar species on different continents that are no longer connected. These are land animals with odd similarities , call it speciation by continental drift. The fact that marsupials are all in Australia except for the opossum, is evidence of this occurring. It implies that at some point the marsupial common ancestor was both in Australia and the Americas.
Additionally there are common fossil records in both South America and Africa, implying that the animal was in both locations and therefore those locations had to be connected.

Geologically speaking there is a bit more evidence. Firstly, there is the fact that the South American coast would fit a little too perfectly into the African coast. Secondly, there are a few examples of mountain ranges lining up, implying that the mountain ranges in question used to be connected. Furthermore these mountains have very similar rock makeup. There is also similar rock strata on different continents that suggest the landmasses were connected.

Most compelling to my mind, is the fact that there are iron rich minerals that formed and lined up according to the Earth's magnetic field. The way this minerals are organized is evidence of the orientation of the Earth's magnetic field at the time. So as the continents moved apart these minerals would no longer line up with the magnetic field. I think this is referred to as Paleomagnetism. Please read up more on it if I have made it confusing.

Finally, the fact that we can observe it happening. Measurements indicate that after the big earthquake in Japan the island moved around 6 feet. We also see seafloors spreading around the world at rates as high as 10 cm/year or even higher.

Anyway, this isn't my area of expertise but I hope I have given you enough information to answer your question.