The Bermuda volcanic pedestal is one of a group of four volcanoes which are situated on an uplifted region of the Atlantic sea floor known as the Bermuda Rise (see illustration below). The group or cluster, aligned NE-SW, comprise the following seamounts: Bowditch, Bermuda, Argus Banks (aka Plantagenet) and Challenger Banks.  These are not a volcanic "chain" in the same sense as the Hawaiian chain, which is thought to have been created by the movement of the sea floor crust over a "hot spot", or upwelling of magma, in the mantle below. For Bermuda to be part of such a chain, the four volcanoes would have to be aligned in the same direction as the movement of the North Atlantic Plate, on which it rides (i.e. towards the northwest).  The alignment, perpendicular to this direction, may simply be due to a linear weakness in the earth's crust. 

BIF  >  Geology > Volcanic origins, Page 1                                      next page >

Dating of volcanic material from exploratory drill holes in Bermuda have yielded ages of between 47 and 33 million years before present, indicating at least 2 episodes of volcanic activity.

 

Direct evidence of the islands' volcanic origins is absent at the land surface, other than scarce occurrences of volcanic sands and pebbles preserved within the limestone  rocks. However, originally, the seamounts would have formed volcanic islands, protruding impressively, up to 1000 meters from the Atlantic Ocean (Vogt and Jung, 1984). Millions of years of battering by ocean waves reduced them to mere submerged stumps and, now, depths to volcanic material  range from 26m below sea level at the eastern end of the Bermuda islands to 75m in the west.      next page >