Carte du Fond des Oceans.

Description

This is a c. 1972 French edition of the famous Bruce Heezen and Marie Tharp map ‘The Floor of the Oceans’.

‘The Floor of the Oceans’ represented a decisive and paradigm shift in the geological understanding of Earth’s history and formation, and the earliest detailed map of the ocean surface, charted by renowned oceanographers Marie Tharp and Bruce Heezen. The map shows the entire surface of the planet but focuses on the ocean floor. Naturally, it has only been possible to document this topography in any detail during the course of the 20th century, with the development of sonar technologies and advances in bathymetric theory. Bathymetry is the maritime equivalent of topography and essentially consists of mapping the surface of ocean floors in great detail, which in this case necessitated an exorbitant number of sonar scans in order to produce low-resolution impressions of the deep-sea floor.

The map is a large offset color lithograph measuring approximately 41 x 27 inches, dimensions suitable for placement on almost any wall. It was primarily intended for schools, boaters, and scholars with oceanographic interests, but was soon recognized as an ideal means of raising public awareness of the incredible topography hidden beneath the ocean surface. This was the first time that this remarkable topography was visualized as a single whole. The American Geographical Society published the chart with formal support from the United States Navy Office for Naval Research. The final product itself was designed and painted by French artist Tanguy de Remur, and printed by Pierre Charron in Paris.

At first glance, the map’s composition may seem strange to viewers. It is clearly a Mercator-type projection (as is indicated in the lower left corner of the map), but the Eurasian and African landmasses have in this case been centrally placed, with the Americas flanking them on either side; the left flank shows all of South America, and the right shows the entire North American continent. The purpose of this arrangement is to show the world’s great oceanic spaces as one coherent entity, thereby providing a canvas on which to reveal the spectacular topography at its floor.

Among the many discoveries Tharp and Reezen made and presented on this map was the existence of a single coherent mountain range connecting the Pacific and Atlantic Oceans. The impressive terrain includes gigantic fracture zones, deep trenches, rift valleys, and several underwater mountain ranges, including the colossal Mid-Oceanic Ridge. Extensive labeling of geological features and ubiquitous depth and altitude measurements make the map accessible, even to a layperson.

Context is everything

This map is the result of thousands upon thousands of sonar images of the seabed. It constitutes an end product of sorts, the outcome of decades of research by American geologists and oceanographers Marie Tharp (1920-2006) and Bruce Charles Heezen (1924-1977). Both worked as oceanographers for the Lamont-Doherty Geographical Observatory of Columbia University. While Heezen specialized in collecting sonar data and extracting verifiable patterns from it, Tharp worked as an oceanographic cartographer and a specialist in geological formations. We have mentioned Tharp’s discovery of the Mid-Atlantic Ridge, a massive chain of mountains that cuts through the middle of the Atlantic Ocean, then circumvents Africa, where it joins the Mid-Indian Ocean Ridge to form an escarpment just south of Arabia (the Carlsberg Ridge). In addition to showing how comprehensive and connected the Earth’s submarine topography is, Tharp also developed new theories on plate tectonics and the phenomenon of continental drift. Until that point, the most common theory of Earth’s geological formation held that the planet was gradually expanding, causing the crust’s tectonic plates to shift.

Among the proponents of this theory was Bruce Heezen, a professor of oceanographic geology at Columbia University. Tharp worked as Heezen’s assistant while they were both younger, and he initially dismissed her first major discovery: a rift valley in the North Atlantic. Yet despite being the senior (and male) scholar, Heezen gradually came to accept Tharp’s views on the formation of Earth’s submarine crust, including identifying the Mid-Oceanic Range as a single coherent geological entity and rejecting the hypothesis that tectonic shifting was due to Earth’s gradual expansion. Soon, he would come around to the paradigm change that Tharp’s research suggested, and together they would go on to produce the first full topographical view of the Earth’s submarine surface.

Marie Tharp was a pioneering figure in science who struggled through repeated rejections of her ideas and research in favor of her male counterparts. Even as her ideas gained traction – to a large degree due to the growing public support of Heezen – she was often not credited for her findings. Today, she is considered one of the 20th century’s greatest geological scholars.

Census and publication information

This map is one of a series of four published between the late 1950s and late 1970s (the North Atlantic Sea in 1957, the South Atlantic Sea in 1961, the Indian Ocean in 1964, and this map of the world’s ocean floors), demonstrating Tharp and Heezen’s research. The current map is the earliest printing of the world map, drawn by Tanguy de Rémur, printed by Draeger, and published by Éditions Pierre Charron in 1972. Despite the scientists’ American nationality and heavy involvement of the American Geographical Society and the United States Navy, this French edition appeared before an English edition (by the same makers, printed in Paris), c. 1976. Although well represented in institutional collections, both the English and French editions of this map are rarely offered at auction.