"This attractive world map is reflective of the rapid scientific advancements in mapping the ocean's floor that took place during the late 1950s and early 1960s. The development of sonar during World War II had innumerable applications, including determining the depth of particular points on the sea bed. According to NOAA, "In 1957, the publication of Heezen and Tharp's physiographic map of the North Atlantic was the first map of the seafloor that allowed the general public to begin to visualize the ocean floor. These early maps, based on hundreds of thousands of hand-picked depths, provided the context for the plate tectonics revolution in the 1960s that finally gave science satisfying explanations for the formation of mid-ocean ridges, trenches, mountain ranges and the "ring of fire" around the Pacific." The image shows a generalized overview of the contours of the ocean floor. Major features are labeled and elevation diagrams provide profiles of both the Atlantic and Pacific Oceans. Details are provided about the Trieste, a bathyscaphe that became the first crewed vessel to descend to Challenger Deep (the lowest known point on Earth) in 1960. The verso shows a chart of marine wildlife and the approximate depths of their environments. Published by C.S. Hammond & Company around 1962, based on the illustration of the research ship Atlantis II, which was completed that year. Distributed as a promotional item to the audience of My Weekly Reader, an educational magazine issued between 1928 and 2012. Source: NOAA" Sheet Width (in) 38 Sheet Height (in) 25.9 Condition Description "Creasing and moderate wear along old fold lines, including about 3" of separation that has been repaired on the verso with archival tape. Discoloration from old cellophane tape (now removed) visible along the edges of the sheet. Wear and light soiling also visible in the corners. About good condition overall."
