Scientific theories change as new evidence is discovered. Alfred Wegener first proposed continental drift in 1915 but it was not widely accepted until the 1960s when technology allowed mapping of the ocean floor and discovery of magnetic stripes on the sea floor, providing strong evidence that the continents were once joined as part of a supercontinent called Pangea. In general, as technology improves it provides new ways for scientists to experiment, make observations, and collect data, which can lead to revisions or replacements of existing theories to better explain new findings. The history of science shows that while ideas evolve incrementally over time, major changes in scientific explanations also occur when compelling new evidence is presented.