Formed by successive eruptions of lava, the volcanoes have proved of immense interest to scientists and geologists, as well as to the people of Pitcairn with the largest hotspot, Adams, rising to 3,500M and coming within 39M of the surface. The Bounty seamount rises to within 450M of the surface and appears morphologically more youthful (350,000 years) than Adams with water samples indicating continuing hydrothermal activity.
The Frenchcompany Ifremer, have used two dedicated ships R.V. L’Atalante and R.V. Nadir and recently completed 15 dives with the submersible Nautile making observations and sampling volcanic structures on the ancient ocean crust of the Farallon Plate, at depths of 3,500 – 4,300M. Their work uncovered evidence that the seamounts were formed by successive eruptions of highly vesicular, alkaline lava flows. Evidence of lava tubes, hydrothermal springs, trachytic lava flows and deposits of iron silicide hydroxides (on Bounty’s peak), have also been found.