Guyot

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A guyot is a flat-topped seamount. Guyots show evidence of having been above the surface with gradual subsidence through stages from fringed reefed mountain, coral atoll, and finally a flat topped submerged mountain. Guyots are very commonly found in the Pacific Ocean, and are considered to be extinct volcanoes. The Emperor Seamounts are an excellent example of an entire volcanic chain undergoing this process and contain many guyots among their older examples.

Guyots were first identified by Harry Hess who collected data using echo-sounding equipment on a ship he commanded during World War II. The data showed the configuration of the seafloor where he saw that some undersea mountains had flat tops. The geology building at Princeton University is, and was, called Guyot Hall (being named after the 19th century geographer Arnold Henry Guyot). Guyot Hall has a flat roof, so Hess called these undersea mountains guyots (because they resembled Guyot Hall). Hess postulated they were once volcanic islands that were beheaded by wave action yet they are now deep under sea level. This idea was used to help bolster the theory of plate tectonics.