Ratak Guyot

Ratak Guyot is a submerged volcanic seamount with a flat summit, a shape geologists call a guyot or tablemount. It lies in the Ratak Chain of the Marshall Islands and is not a normal island above sea level.

A flat top usually records erosion or reef growth near sea level before the volcanic edifice subsided beneath the ocean. That makes a guyot a record of both ancient shallow-water conditions and later sinking.

The rocks and seafloor of the Marshall Islands seamount chains are ancient by human standards, with parts of the volcanic foundation dating to the Mesozoic or later Cretaceous history. Exact ages vary by seamount and sample, so it is safer to say millions of years than to assign one number to Ratak Guyot.

USGS work in the Ratak Chain examined seamount rocks, sediments, and ferromanganese crusts, including interest in cobalt and platinum-bearing materials. A 1984 reconnaissance cruise collected seismic data and samples in the Marshall Islands region. [USGS report](https://www.usgs.gov/publications/geological-and-geochemical-data-seamounts-and-associated-ferromanganese-crusts-ratak).