The coastlines of South America and Africa match like a giant jigsaw puzzle. Centuries back, cartographers already noticed this geometrical fit of continents across the South Atlantic Ocean. In 1915, Alfred Wegener proposed the first scientific hypothesis based on this observation. According to his continental drift theory, continents had changed their relative locations throughout the geological past.

Over the course of millions of years, the coastlines and sea levels were changing. So today, some pieces of the continental jigsaw puzzle result in overlaps and gaps. For piecing it together, submerged continental shelves fit better than today's coastlines. Besides that, Wegener found other evidence to support his theory: