Wegener continued to expand his evidence when sonography was developed. Sonography uses echo signals to map the ocean floor. Sound signals would be sent down towards the ocean floor, and an echo sounder trace would calculate using the time it took for the sound signal to return to the boat, the depth of the ocean floor and that particular point. With this technology accurate maps of the ocean floor could be drawn. It was by using this technology that range of mountains was discovered running down the middle of the Atlantic Ocean. This range of mountains extended for approximately 60,000km underneath the oceans, around the Earth’s surface. Wegener was not the first to suggest that the continents had once been connected, but he was the first to present extensive evidence from several fields.
However Wegener’s theory of Continental Drift was not accepted by many scientists at all. The reactions to Wegener’s theory were almost uniformly hostile and often exceptionally harsh. Even after Wegener’s extensive research and evidence, he still could not explain how the continents had moved as he believed and so therefore his theory was dismissed by many.
It was not until the late 1950s that Wegener’s concept of continental drift was revived. The concept was revived due to further exploration of the ocean floor. It was discovered that there were many differences between the Continental Crust and the Oceanic Crust. It was discovered that the continental crusts are approximately 30km thick, with variations in places, whereas the oceanic crust is uniformly 6km thick a lot thinner than the continental crust. This proved that the continental crust and the oceanic crusts must have been made at different times and in completely different ways. As technology improved and exploration of the oceans floors became more efficient, it was discovered that the rocks forming the ocean floor were mainly volcanic, and highly magnetic.
With further emphasis put on the exploration of the mountain range discovered along the centre of the Atlantic Ocean, even more of these volcanic rocks were discovered, allowing scientist to conclude that these rocks were a lot newer than those found on the continental crust. When it was discovered that these rocks were highly magnetic, scientists used a technique called Palaemagnelism (magnetic striping) to form a diagram of the different magnetic pulls of the volcanic rock along the Mid Atlantic Ridge. It was by using this technique that scientists discovered that the magnetic stripes are symmetrical on either side of the valley in the Mid Atlantic Ridge. It was when scientist discovered this that they could finally conclude that new land was being formed along this range of mountains in the Atlantic Ocean. As scientist explored the valley floor of the Mid Atlantic Ridge they also discovered what are known as Hydrothermal Vents, or are sometimes referred to as Hot Springs. These vents proved that there was volcanic activity. Transform faults were also discovered along the Mid Atlantic Ridge. Transform faults occur when different ends of the oceanic crust move apart at different speeds, and cracks form along the earths crust. This is another indication that the oceanic crust is moving, and that new land is being formed. There was however one fault in Wegener’s theory. Continents do not plough through the ocean floor. Instead, both continents and ocean floor form solid plates, which "float" on the layer, and due to the underlying rock being under such tremendous heat and pressure it behaves as an extremely viscous liquid.
With all this new evidence being discovered, Wegener’s theory was finally accepted by all scientists. It has been proven that South American and South Africa were once joined, as were India and Antarctica. And that 255 million years ago, the super continent Pangaea did exist.