volcanic

The ship drew on and had safely passed the strait, which some volcanic shock has made between the Calasareigne and Jaros islands; had doubled Pomègue, and approached the harbor under topsails, jib, and spanker, but so slowly and sedately that the idlers, with that instinct which is the forerunner of evil, asked one another what misfortune could have happened on board.

It is a rock of almost conical form, which looks as though it had been thrust up by volcanic force from the depth to the surface of the ocean.