Harry Hess: One of the Discoverers of Seafloor Spreading | AMNH https://www.amnh.org/learn-teach/curriculum-collections/earth-inside-and-out/harry-hess-one-of-the-discoverers-of-seafloor-spreading
The idea that continents drift over time dates back to the 1500s, but it wasn’t until the 1900s that scientists figured out plate tectonics.
analyze rock samples brought back from the Moon by the Apollo