When was the first modern map of the seafloor published?

One of the first modern views of the seafloor came in 1953 through the work of Marie Tharp and Bruce Heezen. Their mapping revealed a long rift valley along the Mid-Atlantic Ridge, a feature that helped convince scientists that the ocean floor was geologically active. Tharp’s interpretation was especially important because it supported the idea of seafloor spreading. The map became a landmark in oceanography and Earth science.