How the US Navy Set the Shape of the Heezen-Tharp Ocean Map

Last night’s episode of Cosmos gave a huge shout-out to the Heezen-Tharp ocean map, which sketched the contours of the Atlantic seafloor and gave a huge boost to the theory of continental drift. Behind the story of that success is the heavy hand of the Cold War: one that gave with one hand and took with another.

Oceanography was one of the hottest sciences for the US military in the early Cold War, as the navy looked at ways to understand how to hunt Soviet submarines, hide its own, and navigate across the world’s oceans. Measuring distance, depth, and gravity, among other things, was vital work for naval operations. (If you want a good account of these developments up until the 1960s, read Gary Weir’s An Ocean in Common: American Naval Officers, Scientists, and the Ocean Environment.)

Enter Bruce C. Heezen and Marie Tharp. As a trio of historians of science (Ronald E. Doel, Tanya J. Levin, and Mason K. Marker) explain in “Extending modern cartography to the ocean depths: military patronage, Cold War priorities, and the Heezen-Tharp mapping project, 1952-1959” (Journal of Historical Geography, 2006), it was the military interest in depth measurements that helped generate the data Heezen and Tharp used.

But the military involvement also had an effect on how Heezen and Tharp presented their information. Because the depth data was so militarily important, the US Navy insisted that the precise seafloor depths remain classified. Only by presenting the information in an oblique form, exaggerating the vertical height of the features by a scale of 40:1, were they able to evade this restriction. That’s why the Heezen-Tharp map and its successors have such a striking visual style.

The article goes into a lot more detail, of course, and not just on the secrecy issue. It’s well worth reading if you have access.


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