split-rock

From the appearance of the rocks on each side it is probable that the water having been pent up in the small bay just noticed, have in their efforts to escape undermined the land and rocks at this place, and forced a subterraneous passage, which by wearing, aided by some violent concussion, has caused the rocks to fall in, when the earth being washed away by the rapidity of the current, has left the present passage open, and that the split-rock and the bed of the channel is part of the former overhanging rocks.

History of New Brunswick Peter Fisher 1815