# In 1974, Alvin and two French submersibles descended into the Mid-Atlantic Ridge, made 44 dives and collected 100,000 photographs and 3,000 pounds of rock while giving scientists a close view of how new ocean crust takes shape

> In 1974, a deep ridge in the Atlantic became a working field site for people inside small research vehicles. Three submersibles reached the seafloor near the Azores and watched a basic planetary process at close range. Lava had poured through cracks, cooled...

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Published: 2026-07-24T23:30:02+00:00
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In 1974, a deep ridge in the Atlantic became a working field site for people inside small research vehicles. Three submersibles reached the seafloor near the Azores and watched a basic planetary process at close range. Lava had poured through cracks, cooled and helped create fresh ocean crust between moving plates. That direct view mattered because maps and shipboard instruments could suggest a ridge's shape, while the crews could finally inspect its rocks, fractures and lava forms in place. The question was larger than one valley. Geologists were testing whether their ideas about plate motion matched the landscape beneath the sea. Earlier surveys showed a linked mountain system, yet they could not reveal which formations belonged to its active center or how lava met the valley's fractures. At that depth, a pressure sphere carried lights, cameras and instruments that made direct observation possible.

The expedition was called [**Project FAMOUS**](https://www.whoi.edu/feature/history-hydrothermal-vents/discovery/1974.html), short for French-American Mid-Ocean Undersea Study. It brought together U.S. and French ships, scientists and vehicles. Crewed deep-sea work still faced sharp doubts about cost, safety and scientific value. The effort became a turning point for ocean geology. It showed that careful mapping from the surface and direct observations below could work as one system. The partnership began after French scientist Xavier Le Pichon proposed a joint expedition to Woods Hole geologist Ken Emery in 1971, giving the project a scientific purpose and an international scale from the start.

## A ridge seen at human scale

The target lay on the **Mid-Atlantic Ridge** between 36°N and 37°N, nearly 400 miles southwest of the Azores. The site was about 9,000 feet below sea level. Its rift valley ran between steep ridge flanks that rose about 5,000 feet. For geologists, that setting offered a rare chance to examine the boundary where the North American and European plates pull apart. The valley was deep enough to feel like an underwater canyon, yet it occupied the crest of a mountain chain that circles much of the planet.

Scientists already had strong evidence that new seafloor forms at mid-ocean ridges. Magnetic measurements, earthquake signals, echo soundings and rock samples had built that case. FAMOUS made the process visible at a far finer scale. Crews saw a narrow volcanic zone where magma reached cracks in the seafloor, spread as lava and added material to the ocean floor. Fresh lava can take rope-like, sheet-like, or rounded pillow forms as it meets cold seawater. These textures let observers connect a rock's shape with the conditions of an eruption. The observations helped turn **seafloor spreading** from a broad global model into terrain that geologists could inspect.

## Preparing for a difficult descent

Before the 1974 dives, the partners spent years narrowing the search area. Aircraft measured magnetic patterns above the sea. Research ships used echo sounders and British and U.S. teams added **side-scan sonar** and deep-towed instruments. Sonobuoys and instruments on the bottom recorded earthquake waves, giving scientists clues about rock layers beneath the seafloor. Each survey answered a different question: where the valley lay, how steep it was, where recent volcanic material might be and how the crust was arranged below. The work produced a detailed plan for a place that human observers could explore only a few hours at a time.

**Woods Hole Oceanographic Institution** also prepared the U.S. vehicle for greater pressure. In 1973, Alvin received a **titanium pressure sphere** that extended its rated range from 6,000 to 12,000 feet. Its record, maintained in the institution's [Alvin history](https://www.whoi.edu/what-we-do/explore/underwater-vehicles/hov-alvin/history-of-alvin/), places Project FAMOUS among the submersible's early landmark missions.

Photography was part of the preparation as well. The U.S. Naval Research Laboratory's LIBEC camera system took wide images of the seafloor, while Woods Hole built the ANGUS deep-towed camera sled for the project. LIBEC suspended bright flash lamps above the bottom and photographed strips about 120 feet wide. It gathered 5,250 photographs that scientists assembled into a large visual map before the main expedition. Robert Ballard later wrote, "The preliminary work (for Project FAMOUS) resembled the kind of planning, detailed study, simulation and training that goes on before a major space mission."

## Forty-four dives into fresh crust

In June 1974, the fleet assembled near the Azores. The French bathyscaphe **Archimède** arrived with the ship Marcel le Bihan, while the smaller French submersible **Cyana** traveled aboard Le Noirot. Alvin worked from R/V Lulu, which Woods Hole's R/V Knorr towed. D/V Glomar Challenger stood ready to drill a seafloor core for the Deep Sea Drilling Project. Archimède had already made seven reconnaissance dives during the summer of 1973. That earlier work brought back close photographs and samples that helped refine the plan for the main campaign. Each platform offered a different way to learn from the ridge.

The dive totals capture the expedition's scale. Alvin completed 17 dives and logged 81 hours on the seafloor. Archimède and Cyana added 27 dives, bringing the mission total to 44. The teams collected roughly 100,000 photographs and 3,000 pounds of rock. Those samples included evidence of manganese and iron deposits. The photographs preserved the setting around a sample, including nearby flows, cracks and slopes. The rocks could later be examined for texture, minerals and signs of their volcanic history. Together, the two records gave researchers a way to connect laboratory observations back to a precise place on the ridge. A 1974 [U.S. Geological Survey paper](https://pubs.usgs.gov/publication/70207917) from the same ridge area described a rift valley shaped by volcanic eruptions, splitting and subsidence.

That amount of fieldwork changed what a submersible could contribute to geology. Scientists could follow lava fields, examine fractures, choose samples and place those observations on detailed maps. The **rift valley** was rugged and dark, so the vehicles moved slowly and covered limited ground. A vehicle's lights revealed only a small part of the landscape at once. Navigation and the earlier photographic mosaics kept each dive tied to a wider picture. Their value came from matching close-up evidence with the wider survey. Point-by-point work allowed scientists to compare separate lava fields instead of treating the ridge as one smooth line. The method became a model for later work on the global ridge system.

## What FAMOUS found and what waited ahead

The expedition encountered wide fields of seafloor lava and clear signs of active crust-building. It found no **hydrothermal vents**. By the end of FAMOUS, vents remained undiscovered, a status that changed at the Galápagos Rift in 1977. Woods Hole's account of the [1977 expedition](https://www.whoi.edu/feature/history-hydrothermal-vents/discovery/1977.html) describes how a temperature signal and photographs of clams led scientists to the first direct vent observations. FAMOUS had proved that submersibles could search such difficult terrain.

That distinction matters because vents require a separate chain of evidence. Seawater can seep into newly formed crust, warm near hot rock, react with minerals and rise back through fractures. The resulting fluid can carry dissolved chemicals and build chimney-like structures. NOAA's overview of [hydrothermal systems](https://www.pmel.noaa.gov/eoi/nemo/explorer/concepts/hydrothermal.html) explains why ridges are prime settings for this circulation. FAMOUS supplied a close geological baseline, while the later Galápagos work revealed the hot springs and their remarkable biological communities.

## A later dive tested the method

Project FAMOUS continued into a second year of searching. During a 1975 Alvin dive, Woods Hole scientist Bill Bryan and U.S. Geological Survey scientist Jim Moore traveled with pilot Jack Donnelly across a field of wide cracks. One fissure was wider than the submersible and the team drove into it slowly. The walls narrowed beyond the range of the lights. Alvin became wedged in the crack, with no rescue vehicle available on the seafloor.

Careful records of the vehicle's earlier movements helped the crew work out a route back. White particles drifting through the water gave another clue about the current and Alvin's path. Donnelly retraced the approach and freed the vehicle. He then continued the dive rather than immediately returning to the surface. The episode showed why planning, navigation and detailed observation were essential parts of crewed exploration at a spreading ridge. It also left researchers with a stronger platform for the discoveries that followed.