Final answer:
The Atlantic Ocean began to form around 200 million years ago with the breakup of the supercontinent Pangaea, according to the theory of plate tectonics and evidence presented by Alfred Wegener.
Step-by-step explanation:
The question pertains to the theory of plate tectonics, which describes the movement of the Earth's continents over geological time scales.
According to Alfred Wegener's hypothesis and further geological evidence, the continents of Africa and South America were once part of a supercontinent called Pangaea, which existed around 200 million years ago.
The formation of the Atlantic Ocean began with the break up of Pangaea, an event that approximately dates back to that time period. Therefore, to find the formation of the Atlantic Ocean, you would have to go back approximately 200 million years in geological history.