Earth is unique in our solar system because it is characterised by movements of the tectonic plates that build its outer layer. These movements are driven by energy from decay of radiogenic elements and from primordial heat left over from Earth’s formation. Earth has ca. 15 major tectonic plates, of which the largest are Africa, Antarctica, Eurasia, Australia, North America, Pacific and South America.
Plate reconstructions showing the positions of the plates through time are based on studies of data such as palaeomagnetism, ocean floor magnetic anomalies, the rock record and faunal associations. These studies show that the Earth's plates have moved around over millions of years, colliding together and breaking apart, and sometimes forming supercontinents in which most plates have joined together into a single continent.
An example of a supercontinent is Pangaea, formed around 300 million years ago. Pangaea began to break up around 190 million years ago, at which time Norway was alongside Greenland, which was then part of a continent known as Laurentia. Norway began to separate from Greenland around 55 million years ago, forming the Norwegian Sea as the North Atlantic continued to enlarge towards its present form.
Researchers at NGU investigate the processes of continental break-up, subduction, and collision, and are among those developing GPlates - a software tool for building and visualising plate reconstruction models.