Birth and Evolution of Marine Geological Cartography: Contribution to the Tectono-Sedimentary Understanding of the English Channel

Marine geology is a relatively young discipline compared to the research conducted on land. In France, while the first draft of a geological map dates back to the 18th century (Guettard, 1746), it wasn't until 1980 that marine data on the metropolitan continental margins were integrated into the geological map at a 1/1,500,000 scale, published by the BRGM. Jean-Étienne Guettard, a physician, botanist, and mineralogist, and a friend of Lavoisier, already had the remarkable intuition of a continuity in geological formations across the English Channel. In 1917, Stanilas Meunier, in his "Geological History of the Sea," boldly claimed that the science of marine geology had French origins.

For a long time, the progress of marine geology was constrained by the barrier of the water column. Therefore, initial information about fossil seas came from land-based studies. In Northern France, particularly along the Boulonnais coast, pioneering work was carried out by Pierre Pruvost (1921, 1924) and Auguste-Pierre Dutertre, the latter writing in 1925 a geological report on Pointe aux Oies and the vicinity of the Wimereux Zoological Station in the Glanures Biologiques, published on the occasion of the Station’s fiftieth anniversary (1874-1924).

Louis Dangeard, one of the great pioneers of French marine geology, was the first in the world to publish a thesis in 1928 on a submarine basin, specifically that of the English Channel, after spending 7 consecutive years (1922-1928) aboard the prestigious research vessel “Pourquoi pas ?” under Captain Jean Charcot. Subsequently, in 1933, he succeeded in forming a team of researchers and students to establish the Marine Geology Center of Caen. In France, the first sheets of the sedimentological underwater map of the Atlantic continental shelf of France at a 1/100,000 scale were published in 1968 by the National Geographic Institute, with a remarkable contribution from Louis Dangeard’s former students: Jacques Bourcart and André Guilcher, along with Gilbert Boillot, Pierre Hommeril, Félix Hinschberger, Pierre Giresse, and Claude Larsonneur, working on state thesis topics focusing on the English Channel.

Subsequent work would be closely tied to technological advancements in marine tools, particularly geophysics, after the first oceanographic expeditions of the N/O Challenger (1872-1877). Using archives and historical sources, we trace here the evolution of marine geological cartography, a brief history of oceanographic vessels, and the exploration tools that gradually shaped the tectono-sedimentary understanding of the English Channel.