kontinentalväxlingar

Kontinentalväxlingar, also known as continental drift, is a scientific theory that describes the large-scale horizontal movements of continents across the Earth's surface over geological time. The concept was first popularized by Alfred Wegener in the early 20th century, who proposed that the continents were once joined together in a supercontinent he called Pangaea. He observed similarities in the coastlines of continents on opposite sides of the Atlantic Ocean, as well as matching fossil records and geological formations across these continents, as evidence for this past connection.

Wegener's initial theory faced significant skepticism due to a lack of a plausible mechanism to explain how continents could move. However, the development of the theory of plate tectonics in the mid-20th century provided the necessary framework. Plate tectonics explains that the Earth's outer shell, the lithosphere, is divided into several large and small plates that float on the semi-fluid asthenosphere beneath. The movement of these tectonic plates, driven by convection currents in the Earth's mantle, is what causes the continents to drift and change their positions over millions of years.

The process of continental drift continues today, albeit at a very slow pace, typically a few centimeters per year. This movement is responsible for major geological phenomena such as the formation of mountain ranges, earthquakes, volcanic activity, and the opening and closing of ocean basins. Understanding continental drift and plate tectonics is fundamental to many fields of geology and geophysics, providing insights into the Earth's history and its dynamic nature.