Barrenjoey is a locality in the suburb of Palm Beach, at the most northern tip of Pittwater. The headland is made up primarily of sandstones of the Newport Formation, the top third is a cap of Hawkesbury sandstone. Around 10,000 years ago the headland was cut off from the mainland due to the rising sea level; subsequent buildup of a sand spit or tombolo reconnected the island to the mainland (a 'tied island'). It is the location of the Barrenjoey Head Lighthouse, a lighthouse that was first lit in 1881. In 1995 Barrenjoey was gazetted into Ku-ring-gai Chase National Park.