Celebrating the Pioneering Cartography of Marie Tharp and Bruce Heezen

“I had a blank canvas to fill with extraordinary possibilities, a fascinating jigsaw puzzle to piece together: mapping the world’s vast hidden seafloor. It was a once-in-a-lifetime—a once-in-the-history-of-the-world—opportunity for anyone, but especially for a woman in the 1940s.” Marie Tharp.

A few weeks into my exploration of the University College London Geography Map Library I happened upon two drawers filled with vast “physiographic” maps.

These were not conventional contour maps, but textured, almost sculptural views of the Earth’s surface. Many were by Armin Lobeck and Erwin Raisz, pioneers of the approach, which was especially popular in the 1940s and 1950s.

Among the maps of mainland Europe and North America were three enormous ocean‑floor maps — spanning the South Atlantic, the Western Pacific, and the Indian Ocean — created by Marie Tharp and Bruce Heezen.

Tharp is now one of the most celebrated cartographers from the 20th Century (even being featured as a Google Doodle in 2022). The maps of the ocean floor she produced with Heezen transformed our understanding of the landscape beneath the waves, simultaneously capturing the imagination of millions but also informing the theory of plate tectonics: one of the most important scientific breakthroughs of the postwar era.

When I first found these maps I recognised Tharp’s name, but I knew little about how these maps had been made. My curiosity got the better of me, so I extended a pre-booked trip to Washington to spend several days sifting through Tharp’s vast archive housed at the Library of Congress.

Only there did I truly understand the scale and ambition of the maps of the ocean floor she dedicated her career to.

There so much fantastic material that has already been written about Tharp and her legacy (I’ve listed some at the end), but nowhere have I found the most signficant maps she helped to create gathered in one place.

So I have created a chronology of these ocean floor maps to show how they became some of the most well-known and influential maps of the twentieth century. I know there are a few I’ve missed that are in National Geographic atlases and on globes, but the fifteen below show the most comprehensive evolution of the ocean floor mapping work I’ve found to date.

I’ve kept the text to the minimum here, but if you want to read my detailed version of the story it can be found in the later chapters of The Library of Lost Maps!

n.b. Images below are largely scanned from maps held by UCL Geography/ my own collection and used here for educational purposes. The maps remain in copyright so permission for re-use should be sought from the relevant holders.

1. Physiographic Diagram Atlantic Ocean (1957)

In September 1957 Heezen co-authored a paper in The Bell System Technical Journal titled “Oceanographic Information for Engineering Submarine Cable Systems”. It was a specialist paper for engineers interested in laying cables, but in the back was the “Physiographic Diagram Atlanitc Ocean”, which was the first of Tharp’s major creations.

Detailed bathymetric contours were considered militarily sensitive at the time, so Tharp and Heezen took a different approach. Instead of only charting precise depths, they focussed on the terrain and shapes of the seafloor and deflty skirted the censors.

The result was an entirely different impression of what the bottom of the ocean looked like. Gone was the idea that it was flat and featureless: the map suggested something much more textured and intriguing.

This map was also significant as Tharp had sketched in a rift valley along the centre of the Mid-Atlantic Ridge. She had deduced its existence from assembling cross‑sections of depths and noticing a V‑shaped indentation in all of them that could be aligned to indicated a vast fracture splitting the ocean floor.

At first, the idea was dismissed, not least by Heezen, who like many geologists of the time, found the notion uncomfortable. A rift implied movement. And movement, in turn, hinted at continental drift — an idea that was still considered controversial.

But Tharp’s data became impossible to ignore, so in 1957 (the same year as the physiographic map), Tharp, Heezen, and Maurice Ewing published their findings, announcing the rift valley as a major feature of the ocean floor. The media seized on the story. Headlines proclaimed that the world was “cracking up.”

In the Library of Congress is a globe that Heezen has painted over to show the key geological features of the seafloor, not least his vision for a “world girdling” rift valley (in red) which dissected the oceans.

The combination of a map that transformed deep from a featureless plain to a dramatic series of mountains and canyons, and the finding that Earth was “cracking up” ignited the public’s imagination and caught the attention of the biggest magazines of the era.

2. The Newly Discovered World Beneath the Waves (1959)

Tharp and Heezen’s data found its way into magazines like Life and Fortune, illustrated by some of their most skilled graphic artists. Among the first was Richard Edes Harrison, whose 1959 world map of the ocean floor brought this hidden landscape into homes and classrooms. He used an innovative projection that helped to create this single ocean view as he explains to readers:

“The surface of the earth has been cut, like the skin of an orange, along the American continents (at longitude 70° west) and pressed flat in such a way that the relative sizes of all areas are free from distortion.”

I think this is the first global map of the ocean floor that includes the data processed by Tharp and Heezen. It is printed on very shiny paper – in subtle colours – so was very hard to do justice in a photo!

3. The New Portrait of Our Planet (1960)

Kenneth Fagg’s rendering, published in 1960, is one of my favourites. It is huge poster that splits Earth into four hemispheres set on a near black background. Life Magazine also included it within their “Life Nature Library” books. He chose to colour the floor by sediment type, which makes Earth look more like Mars, but Heezen felt was slightly “too bold”.

4. The Floor of the World Ocean (1961)

In 1961 Edes Harrison produced a second map in much more muted tones to Life’s version as a supplement to an academic journal. It was printed much larger in comparison to his original version and without the ocean currents on the top. The thicker, uncoated, paper gives the map a much classier feel than the glossy magazine format of his first version.

5. Physiographic Diagram of the South Atlantic Ocean (1961)

Buoyed by the success of their first map and the interest it generated, Tharp and Heezen pushed on into the early 1960s with their physiographic maps. They benefitted too from a wealth of data that was being gathered on numerous expedition ships. In 1961 they published what was to be the largest in the series: the South Atlantic Ocean…which was followed by the Indian Ocean in 1964.

6. Physiographic Diagram of the Indian Ocean (1964)

7. Indian Ocean Floor (1967)

The yellow and blue physiographic giants could be purchased for a few dollars and sent out either folded or in tubes. These maps appealed to a fairly niche crowd of geologists and oceanographers, and certainly weren’t going to make Tharp and Heezen as well known as they are today.

It wasn’t until the late 1960s that National Geographic Magazine initiated a collaboration that would define the visual language of the ocean floor for generations. They paired Tharp and Heezen with an Austrian artist named Heinrich Berann. The three of them would collaborate for over a decade, with Berann taking Tharp and Heezen’s processed data and sketches to create his own renderings under their careful supervision.

The first result was a map of the Indian Ocean, published in 1967. It amazed millions of readers with this unfamiliar perspective and shocked them with the sight of great fissures carving up the Indian Ocean. The success of the map led to a second comission for the Atlantic Ocean in 1968.

8. Atlantic Ocean Floor (1968)

Probably the most recognisable of the National Geographic Maps is the “Atlantic Ocean Floor”. Whilst being visually stunning, it also shows a further breakthrough by including “transform faults”. These are large cracks that can be seen running perpendicular to the Mid-Atlantic Ridge and are caused by the tension of the plates either side of it moving at different speeds along their length (plate tectonics was by now a widely accepted theory) .

Below is I photo I took (standing on a stepladder!) of the “South Atlantic Ocean” alonside the National Geographic poster to demonstrate just how large the former is – and how much Berann squeezed into the latter!

9. Western Pacific Ocean (1971)

The final map from Tharp and Heezen in their physiographic style is of the Western Pacific Ocean. I love how Tharp breaks the neatline around the edge of the map to squeeze in (most of) New Zealand and Australia.

10. Pacific Ocean Floor (1969)

The penultimate map published in National Geographic Magazine was of the Pacific and, finally, the Arctic followed two years later…

11. Arctic Ocean Floor (1971)

Thanks to National Geographic and the collaboration with Berann, millions — perhaps tens of millions — of people had seen the ocean floor in a whole new light by the start of the 1970s.

12. Carte du Fond des Océans (1973)

National Geographic went ocean-by-ocean, so it had been over a decade since any illustrators had tackled a global map of the ocean floor. Then in late 1968/early 1969 the geologist Xavier Le Pichon commissioned an illustrator named Tanguy de Rémur to create a world map (in French) based on the available maps including the physiographic maps that Heezen and Tharp had completed. “Carte du Fond des Océans” was the result.

In the back catalogue of Heezen and Tharp’s maps the de Rémur map is often mistaken for one that they had a direct hand in. This is understandable because it has clearly drawn inspiration from the National Geographic maps and, what’s more, a later edition was published in english under the banner of the American Geographical Society that is credited to Heezen and Tharp. In this case their exisiting maps were used but to my knowledge they did not supply data and supervision in the way they had for the other maps

13. The Floor of the Oceans (1976)

The map above was sold by the AGS to raise much-needed funds for the society.

14. Physiographic Map of the Earth (1975)

Now this map by William Chesser, published in 1975 to accompany the textbook Exercises in Physical Geology by W. K. Hamblin & J. D. Howard, is the one I know least about! I spotted no reference to it in the Tharp archive but she and Heezen are prominently credited as data sources.

It is the only map in the physiographical style of the entire globe to include land and oceans I have found and is probably not as well known. Not least because it lacks some of the visual impact of the de Rémur map that was doing the rounds at the same time. It would also have been eclipsed by what would be Tharp, Heezen’s and Berann’s final map…

15. World Ocean Floor Panorama (1978)

In 1974, with support from the US Office of Naval Research, work began on what would become the World Ocean Floor Panorama.

This was not a compilation of previous maps, it was a painstaking re‑evaluation of the underlying data. Heezen and Tharp returned to original soundings, refining details across every ocean basin. In his studio near Innsbruck (Austria) Berann, joined by his assistant Heinz Vielkind, translated Tharp’s sketches into a continuous, rolling vision of the planet.

Tharp and Heezen travelled to Austria to oversee the work and by 1977 it was finished. They were able to carefully roll the map and fly back with it to the US.

The first print tests were completed just before they headed off on a research voyage to the coast around Iceland. It was on this trip that tragedy struck and Heezen died suddenly of a heart attack while exploring the Reykjanes Ridge in a submarine. Tharp learned of his death by radio, while aboard another research vessel.

Upon her return, and after making arrangements for Heezen’s repatriation and funeral, Tharp continued pushing to get the map printed. She refined the colours, oversaw the labelling, and arranged the printing. When World Ocean Floor Panorama was finally published in May 1978, it bore a dedication from the United States Navy honouring Heezen’s contributions.

Getting to see the orignal up close (in the Library of Congress) was an extraordinary experience. Berann and Vielkind had created a map that looked like a 3D model not a 2D painting. It stands alone as a stunning artwork. You can see the full size scan here.

Final thoughts

Half a century after is was published, the “World Ocean Floor Panorama” map and others that Tharp and Heezen had a hand in still sit at the top of the Google rankings — unmatched in clarity and beauty.

In an era before digital cartography, Tharp and Heezen estimated that over fifty million maps based on their work were already in circulation. Today, that number must be vastly higher. Billions of people have absorbed an understanding of the Earth shaped by Marie Tharp’s vision.

Further Reading

I wanted to pull together what I see are the fifteen most important maps that Tharp and Heezen were involved in to provide cartographic inspiration and broaden their canon beyond the “World Ocean Floor Panorama” which is the most frequently used to illustrate Tharp’s story. But there is so much more to say!

So if you would like read more about how the maps were made and how they influenced the science of the time, this is what I write about in The Library of Lost Maps so do pick up a copy!

If you would like to know more about Tharp’s life and her relationship with Heezen (and others in the scientific community) I heartily recommend Hali Felt’s book: Soundings.

The Library of Congress is home to the Tharp archive and has published several articles and blog posts about it. See here and here for two recent examples.

And if you are a cartographer looking to create your own maps in the Berann style see here.