New England Seamounts Once Near Surface
Exploration of the New England Seamount chain by the research submarine Alvin confirmed that some of these peaks, now all a kilometer or more below the surface, were once at or above the surface of the ocean.
This undersea mountain chain contains more than 30 major peaks and stretches 1,600 miles southeast from the New England coast. Deep-sea dredging has previously brought up Eocene limestone of shallow-water origin from the submerged mountain tops, but the Alvin explorations resulted in the first eye-witness accounts of dead coral (which grows only near the surface) and rock samples containing strands of dead algae that grows only within 100 meters of the surface. The New England Seamounts have therefore either subsided on the order of a kilometer since Eocene times or sealevel has altered drastically.
The Alvin dives also discovered a series of very striking and perplexing buttes obviously the results of erosion (see drawing on cover). The buttes are apparently composed of volcanic rock and are only a few meters high. Some unexplained, extremely vesicular (holefilled) rocks seen on the sea floor during the dives seem to be identical to samples occasionally dredged up and formerly classified as cinders jettisoned from old steamships. The underwater surveys suggested that these "cinders" have a natural (still mysterious) origin.
(Heirtzler, J.R., et al; "A Visit to the New England Seamounts," American Scientist, 65:466, 1977.)
Reference. Guyots pose several enigmas, see ETH1 in our Catalog: Carolina Bays, Mima Mounds. Ordering information may be found here.