What many people can recognize is that the coastlines of eastern South America and West Africa could fit together like a jigsaw puzzle. This was noticed in the 17th century, and it was not until 1912 that Alfred Wegener proposed that all the land masses of the world had originally been connected as one super-continent, which he called
Pangaea
. In the 1960’s scientists were able to explain this when they discovered that the rocky plates of the Earth’s lithosphere were moving, floating on more mobile rock that was below.
As well as matching coastlines, there is other evidence that there was once a single continent. There are fossil and ancient mountain remains on the coastline of completely separate continents. The distribution of the continents can be seen over the past 200 million years.(see figure 3 in appendix) Today, this drift continues. The Atlantic Ocean is getting wider by a few inches each year, the Pacific Ocean is getting smaller, and the Red Sea is part of a crack in the Earth’s crust that will widen to produce a new ocean millions of years in the future.(for further explanation see figure 4 in appendix)
Scientists think that the spreading may have been caused by the convection currents of hot mantle rising under the Earth’s lithosphere plates. The hot mantle comes from deep within the Earth. When it rises, it presses against the lithosphere, pulling it apart. Finally, as the two plates continue to pull apart slowly, then orange-hot magma rises up to fill the gap much the same way a cracked egg oozes out when it is boiled. Throughout history volcanoes have erupted creating new crust and a ridge of mountains along the seams, or rifts.
The word “tectonics” comes from the Greek word
tekton
, meaning “builder.” The theory suggests that the surface of the Earth is made up of the rigid plates of lithosphere which “float” on top of the more mobile asthenosphere. Reaction to the movements in the asthenosphere make these plates be in constant motion. This theory explains many of the major processes of the Earth, such as continental drifting, mountain building, ocean trenches and valleys, and earthquake and volcanic activity. All of the aforementioned are found along plate boundaries or former boundaries.(see figure 5 in appendix)
See activity for creation of different mountain. This also goes along with plate tectonics and continental drift.