Project FAMOUS

The Project FAMOUS study area was located on a section of the Mid-Atlantic Ridge about west of the Azores (Sao Miguel) at 36° 50’ north latitude. It includes a -wide median valley or rift valley on the crest of the Mid-Atlantic Ridge that trends slightly east of north. Within the median valley lies the present boundary between the North American and African tectonic plates. The floor of the rift valley is deep and wide and the bounding rift mountains are at a depth of about , or about above the floor. The rift valley is long and it is offset to the eastward in the north at Fracture Zone A; in the south, it is offset westward at Fracture Zone B. == Methodology ==

in 1978 A significant obstacle in marine surveys was the use of echo sounders with a wide transmit beam, which smeared-out details of the sea floor features. The crustal accretion or creation process was thought to take place over a few kilometers width of sea floor, advanced surface ship sonar, and geophysical measurements, seismology, deep-towed instruments, large format bottom photography, fixed on-bottom instruments, and on-bottom dives with research manned submersibles in the rift valley of the Mid-Atlantic Ridge. The Woods Hole Oceanographic Institution (WHOI) in Massachusetts provided surface ships and the submersible ALVIN; the French provided surface ships and the bathyscaph Archimède and submersible CYANA. The British conducted side scan sonar surveys and on-bottom seismic experiments. Lead institutions were WHOI and the French Centre Oceanologique de Bretagne, Brest, France. With Project FAMOUS located on the ridge in more clement latitudes around 37° N, a coordinated multi-national, multi-ship series of more than twenty expeditions took place over four years, between 1971 and 1974. == Main results ==

Project FAMOUS represented a new experimental approach to sea floor geology and was considered a major technical achievement at the time. and on the East Pacific Rise at 21° N. The project succeeded in defining the morphology and structure of the spreading center or median rift valley along with locating the zone of crustal accretion in the median valley floor. with the rift mountains on the west about 11 km from the deepest part of the valley floor, and those on the east about 20 km from it. This finding indicated that seafloor spreading here is not the same on either side of the valley floor as might be expected with the most simple idea of the process. Instead, the computed rate is 7 mm/year to the west and 13.4 mm/year to the east. These efforts observed the zone of crustal accretion aligned along the center of the valley floor. In the FAMOUS area valley floor the accretion zone is marked by several low and elongate volcanic hills about 100–250 m high and 1–2 km long. Sediment covers most of the inner valley floor away from these hills indicating accretion is not taking place beyond the hills. with volcanic activity recurring every 5,000 to 10,000 years. The observed continuous background seismicity infers that faulting is continual and ongoing. These mark the transform faults between adjacent spreading centers and rift valleys. Because the fracture zones are up to 10 km wide in places, this observation indicates the shear zone or transform fault, migrates over time within the fracture zone itself. These observations; of the architecture of the median valley, of the fracture zone transform faults, and of the crustal accretion zone, mark the first ground-truth data of plate boundaries for a slow rate spreading center. == Further reading ==