The lighthouse stands on a sheer cliff eroded by wave action from a diabase sill containing inclusions of anorthosite. The octagonal building is a steel-framed brick structure with concrete trim on a concrete foundation set into the rock of the cliff. It is topped with a large, steel lantern which features a third order, bi-valve type Fresnel lens manufactured by Barbier, Bernard and Turenne Company in Paris, France. The tower was built for a second order lens, but when construction went over budget, only enough funding remained for the smaller third order lens. The lens floats on a bearing surface of liquid mercury which allows near frictionless operation. The lens is rotated by an elaborate clockwork mechanism that is powered by weights running down the center of the tower which are then reset by cranking them back to the top. When completed, the lighthouse was lit with a kerosene oil vapor lamp.