Each of the seven pilings of this lighthouse had a screw at its bottom so the legs could be screwed diagonally into the soft Bay bottom, creating a more stable foundation than simply driving them straight into the mud. The screws also helped hold the lighthouse secure in winter, when ice froze around the pilings and rising tides tried to lift them. Screwpile lighthouses were an important innovation because they could be built in the middle of the Bay and seen by boats far from shore, but winter ice remained their greatest enemy. As tides rose and fell beneath a frozen Bay, the moving ice placed enormous pressure on the lighthouse’s slender legs. Thirteen screwpile lighthouses were destroyed by ice, and nearly every screwpile lighthouse was damaged. Only four remain today, and just one is still in its original location; the other three, including this one, were moved to land for preservation.