The World Ocean Floor Panorama by Marie Tharp, Bruce Heezen and Heinrich Berann, completed in 1977. The map forced the world’s geologists and oceanographers to look at the ocean floor from a completely new perspective. Tharp and Heezen had previously created maps of individual oceans, such as the Atlantic Ocean and Indian Ocean, but this was the first map to show how all the subsea mountain ranges link together.
Eight months after Tharp had started to interpret the sonar readings, she was able to outline an almost continual rift that stretched all the way around the Earth–a 6,500-mile-long underwater formation, probably the largest geological structure in the world. Now even Heezen was convinced of continental drift.
THE EARTH CRACKS | But Tharp and Heezen didn’t dare release the news immediately–only four years later, in 1956, did Heezen and Doc finally compose an article–full of reservations and caveats–about an ‘apparent’ rift. That same year, Tharp redrew the map of the North Atlantic ocean floor. But it was impossible to impose the reservations made in the article on the map–on the map, the rift was clear. ‘And like the cartographers of old, we put a large legend in the space where we had no data. I also wanted to include mermaids and shipwrecks, but Bruce would have none of it,’ Tharp wrote later. The article and the map formed the basis for the New York Times’s story about the Earth ripping apart at the seams.
Most geologists refused to believe what they saw on Tharp’s map. ‘They not only said it wasn’t fair, they said it was a bunch of lies,’ she said. Her peers were insistent when the first International Oceanographic Congress was held in New York in the autumn of 1959. ‘Some 800 scientists from East and West were told here today that they seemed to be drifting apart–not politically, but geographically,’ wrote the New York Times. While Heezen was giving a presentation, one geologist called out: ‘Impossible!’
The star of the conference was the French underwater photographer and film-maker Jacques Cousteau. Heezen had met him the previous year, and given him a copy of the map of the North Atlantic. Cousteau had hung the map on the wall aboard his ship so that he could study it, and when it was time to cross the Atlantic to participate in the conference, he decided to prove Tharp and Heezen wrong. He filmed the area where the rift was supposed to be.
‘Gentlemen,’ Cousteau began one evening, addressing the handsome tables set for a dinner party for the conference participants, ‘I did not believe that the map of the North Atlantic recently published by Lamont could possibly be right. I did not believe that the Mid-Atlantic Rift pictured on it could possibly be right. Too complete a story, I thought, from too little information. But it is there. It is true.’
The lights were dimmed; the projector hummed to life… 3–2–1… and there was the ocean floor, sand, starfish and, further away, a dark area that, when the camera moved closer, was revealed to be a mountain range. The camera continued to film the mountainside, right until it reached the peak. And there, down below, was the rift–visible for as far as the camera cast its light. Tharp was finally able to see that which for the past seven years she had only been able to imagine.
Tharp used the next four years to draw a map of the southern part of the Atlantic, which was printed and published by the Geological Society of America, and in 1972 travelled with Heezen to Iceland to study the part of the Mid-Atlantic Ridge–and the rift–that can be walked across in the area. Aboard a plane flying above the island, Tharp drew sketches of the rift’s formations.
BLACK GOLD | That same year, French planes took to the skies in Operation North Sea–a project to find out whether there were opportunities to find more oil and gas in the area than the Dutch had discovered along the coast three years previously. The aircraft explored the magnetism of the rock types below the surface. The sediments–the porous rocks in which oil and gas are generally found–are not magnetic, while the bedrock is. By combining magnetic soundings with ordinary ones, it is therefore possible to determine the thickness of the sedimentary layers.
Few were convinced that oil and gas would be found off the Norwegian coast–in 1958, geologists had submitted a letter to the Norwegian Ministry of Foreign Affairs, in which they presumed the continental shelf consisted of the same rock types as those found onshore. The Ice Age was thought to have scraped away the sediments. ‘One may discount the possibility that coal, oil or sulphur may be found on the continental shelf along the Norwegian coast,’ they wrote. But in the following year, Maurice ‘Doc’ Ewing from Lamont published a report on the Norwegian waters, in which he described indisputable findings of sedimentary rock types in the sea west of Trondheim. But his report never made it into the right hands.
In Denmark, exploratory drilling had been undertaken on Jutland for twenty-five years without oil being discovered, and so it was not the search for black gold that motivated geophysicist Markvard Sellevold to start exploring Skagerrak in 1962. He was more interested in mapping the geological border between Denmark and Norway–the place where the Norwegian bedrock gave way to the Danish sediments. Sellevold and his team set up seismic field stations along the coasts. They put 100 grams of dynamite and a lit detonator in a blown-up paper bag, then threw this overboard, repeating the process again and again in order to analyse the seismic sound waves. The Norwegian Geological Survey also measured magnetism in the area from the air, and to everyone’s great surprise the results showed that the sediments stretched all the way to the pebbles on Norway’s south coast–and that just twenty kilometres offshore was a sedimentary layer 5,000 metres thick.
In the application made to the Ministry of Foreign Affairs regarding further exploration of the continental shelf, emphasis was placed on the fact that ‘these sediments are potential carriers of deposits of oil, natural gas, coal, iron ore, etc…’. In 1963, the Norwegian Geological Survey performed ten aerial expeditions to survey the conditions between Stad and Lofoten. The map showed that the magnetic patterns clearly changed in the transition from land to sea, and the results were so promising that a further twenty aerial expeditions were carried out between Loftoen and Senja the following year. The flights were followed by detailed surveys. On a ‘Bathymetric Chart of the Norwegian Sea and Adjacent Areas’, an anonymous bureaucrat has placed an ‘A’ off the coast at Vardø and another off the coast of Florø, and written in ballpoint pen on the mainland: ‘A-A Contact basement sediments.’ In other words: possible oil and gas deposits along the entire coastline. And of course the oil companies were interested now, too. An increasing number of foreign vessels on mapping assignments docked at the quay in central Stavanger, their holds full of explosives for use in seismic surveys.
The Norwegian authorities now understood that the North Sea was a potential gold mine, and on 31 May 1963 the Norwegian government declared the seabed and subsoil in the areas off the Norwegian coast subject to Norwegian sovereignty.
Just 200 years after Norway and Sweden had finally agreed upon the border between the two countries, and 140 years after the latest agreements with the Russians in the far north, Norway was forced to enter into negotiations with the British and the Danes regarding how far out to sea the country’s boundaries extended. The border with Sweden had taken almost 100 years to establish, but the negotiations with the UK and Denmark were settled much more quickly. In 1965, all parties agreed to use the centre-line principle–to draw a line that split the waters between the countries equally. Norway was then able to seek applications from oil companies wishing to undertake exploration activities, and a single-column entry in the Norsk Lysingblad, a state publication for public announcements, kicked the whole thing off: ‘Applications shall reference the field and block numbers specified in this announcement, based on the map deposited at the Royal Norwegian Ministry for Trade and Industry.’
The Map of the continental shelf shows Norwegian waters south of 62 degrees north. Across the south-western area a patchwork of red, yellow, green and other colours indicates which oil companies have been licensed to perform exploratory drilling in the various fields.
The Norwegian oil age had begun.
OCEAN PANORAMA | At around the same time, a young girl from Austria sent a letter to National Geographic. She had seen the magazine’s maps, she wrote, and believed that her father was able to draw much better ones. According to Tharp, the magazine had a weakness for letters from children; in any case, they sent their head cartographer to Austria to investigate–the girl’s father, Heinrich Berann, had drawn many maps of the Alps–and so began Berann’s long collaboration with National Geographic. In 1966, he was put in touch with Tharp and Heezen because the magazine wished to give its readers a map of the Indian Ocean–a large map that could be hung on the wall.
Berann had developed his technique based on the physiographic diagrams Tharp had started with in order to make her maps easier to understand, but while Tharp drew her maps using inks and pens, Berann was a painter, who used brushes and an abundance of colour. His aim was to paint as photographically and realistically as possible. Using light green for the shallow waters and continental shelves, a medium blue for the plateaus, a dark grey-purple for the smaller mountains closer to the surface and an even darker colour for the deepest trenches, Berann enabled everyone to see the peaks and troughs that lay hidden beneath the ocean.
The map was a hit among both geographers and readers, and National Geographic followed its success with a double map. On one side was ‘the visible face of the Atlantic and the lands around it’, on the other the same map, minus the water. The maps were distributed to six million American families.
Berann, Tharp and Heezen created two more maps for National Geographic: one of the Pacific Ocean and one of the waters around Antarctica. Tharp and Heezen then suggested that they create a panorama that illustrated how all the subsea mountain ranges were linked together, and how all the seas and oceans are actually interconnected to create a single great world ocean. The magazine wasn’t interested–but the U.S. Office of Naval Research was, and in 1974 Tharp and Heezen began what would be their last project.
Berann created a large, specially designed board for the panorama. He outlined the land masses, applied a blue background colour to the ocean areas, and started to add in details from Tharp’s drawings. Tharp updated the areas in which new information had become available since she first drew her maps, while assistants did the groundwork of collecting data from the large seafaring nations. Tharp’s home looked like a cartographic production line, with people creating overviews of rifts, mountains and trenches before others created sketches based on these–and still others combined the sketches with sounding data, and so on. Tharp then created drawings for the map, which for the first time would show the 70 per cent of the Earth’s surface that lies underwater.
In May 1977, Tharp and Heezen moved in with Berann to complete the enormous project. We can imagine them leaning over the map in Berann’s study, with its smell of paint, solvents and coffee. The map measures almost two metres across, the blue, black and purple ocean floor presented in cool contrast to the yellow-green and brown land masses. Berann has made between thirty and seventy changes to the map every day since the two geologists arrived. Tharp studies the Bering Strait, the Kamchatka Peninsula and the Aleutian Islands, and says: ‘I think…’
‘Please, Mary, please, no more changes,’ says Berann in his broken English.
Tharp slumps down into a chair. ‘I was just going to say that I think everything looks good.’
One month later, Heezen would travel to Iceland to study the rift valley of the Mid-Atlantic Ridge at close quarters from a submarine. He suffered a heart attack and died there in the depths, aged just fifty-three.
Heezen saw just one of the panorama test prints before he passed away; after his death Tharp was left responsible for ensuring that the printing process provided the right results. ‘I realized that color was not my forte,’ she wrote after noticing that something was wrong with the test print but being unable to determine exactly what. A photographer friend pointed out that the printers had failed to add the colour red. This was the first delay of many, but just under a year later, at 7 p.m. on 17 May 1978 following several adjustments to both the colours and typography, the first copies of the World Ocean Floor Panorama began to roll off the press.
SATELLITES | The panorama is not an accurate map. Despite the immense amount of work behind it, it was based on the geologists’ more and less educated guesses, and much of the panorama has been corrected and updated since it was made–as maps always are. Despite the fact that Tharp and Heezen possessed more knowledge of the ocean floor than anyone before them, given the vastness of the ocean, they knew ridiculously little. Tharp had, for example, just one set of sonar data that provided information about a 640-mile-long mountain range between Australia and the Antarctic, and this was therefore ‘of necessity sketched in a very stylized manner,’ she wrote. All the formations are also highly exaggerated, which is necessary–otherwise even a mountain with a height of 8,000 metres would be invisible on a map of the panorama’s scale.
It is therefore not possible to use the map to find a specific mountain beneath the ocean’s surface, as there is no guarantee that the mountain was included. In 1984, a team of oceanographers used the map when exploring the rift in the southern Atlantic Ocean–the rift was found twenty-four miles from where the map indicated it should be.
Oceanographers like to point out that the Moon has been more accurately mapped than our own planet. Even Venus–which at its closest is forty million kilometres away and covered by thick, poisonous gases–was mapped more accurately than the Earth when the Magellan satellite and its radar passed above the planet in 1992. This was able to map formations on the planet’s surface larger than 300 metres–a level of detail oceanographers can only dream of.
The problem with radar is that it can’t penetrate water, and so sonar remains the most accurate method of mapping the ocean floor. But boats are small and slow, while the ocean is vast–so immensely vast. Only between 5 and 15 per cent of the ocean floor has therefore been mapped using sonar, depending on how one defines mapped.
But satellites have also been used to map the ocean. In 1985, the United States Navy sent up the GEOSAT satellite to measure the height of the ocean’s surface. Even calm waters are never actually flat; they feature hills and valleys with differences in height of several hundred feet, but these are so gradual that ships are unable to detect them. Some of these variations occur where oceanic currents collide, such as where the cold part of the Atlantic meets the warmth of the Gulf Stream, but the biggest differences in height are the result of the Earth’s gravity, which is stronger in some places than in others. The GEOSAT map therefore shows both the height of the ocean surface and the distribution of gravity across the planet.
The GEOSAT map looked familiar to geographers–it looked like a map of the ocean floor. The reason for this is that gravity increases where there is significant mass, such as a mountain range, but decreases in flat areas and at significant depths. The ocean surface is an echo of the ocean floor.
David Sandwell and Walter Smith, American geophysicists and oceanographers, compared the measurements taken by GEOSAT and the European satellite ERS-1 with true soundings in order to establish the accuracy of the satellites’ measurements. In 1997, they published a map that showed much of the ocean floor terrain that was previously unknown. ‘This map is going to focus our attention on some places where we had not usually gone with ships, because they’re in remote areas in the Southern Ocean, they’re far from ports, and the weather down there is uncomfortable,’ said Smith.
Sandwell and Smith continued to work with improving the original map, and in 2014 launched a map based on data from the European satellite CryoSat-2 and American satellite Jason-1. The map was two to four times more accurate than the previous one, and registered formations on the ocean floor measuring five kilometres or greater–but this is still far less accurate than the Magellan satellite’s mapping of our neighbouring planet.
INTO THE DEEP | The mapping of
the ocean floor has been–and continues to be–a tedious and difficult task. Technological developments have progressed from ever-longer plumb lines to sonar and satellites, but there is still a fair way to go to obtain a complete and accurate map of the entire ocean floor. But perhaps such a map isn’t truly necessary. One of Bruce Heezen’s former students, oceanographer Bill Ryan, who has developed various tools for mapping the ocean floor, believes the creation of a complete map to be a waste of time and money. ‘The fact is we can learn how this planet works by seeing five percent of its surface. The next 95 percent looks like the first five percent,’ says Ryan, who would rather prioritise the mapping of the various regions that form the marine opposites of the Alps, tundra, desert and so on. Tharp and Heezen’s map featured only around ten different types of landscape–Ryan believes closer to 200 are required in order to accurately represent the ocean floor. But we need only explore one of each thoroughly, Ryan believes–because once you’ve seen one, you’ve seen them all.
Ryan may well be right. But it is hard to imagine that humankind will stop before the ocean floor has been mapped down to the tiniest detail. Information will be collated, and scientific expeditions to Atlantic, Indian, Arctic, Pacific and Southern waters–the world’s five oceans–will continue to contribute pieces of the puzzle until, one day, the map of the ocean floor will finally be complete.
Global Marine Gravity, Version 23.1 from 2 October 2014. The map was made by geophysicists David Sandwell and Walter Smith using satellite images that show where gravitation is strongest. Where gravity is strongest mountains are probably present; it lessens in flat areas and at significant depths. Gravity is therefore able to provide us with information about the appearance of the ocean floor.
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