The Waitakere Ranges parallel the west coast some 15 miles west of Auckland city and extend as a series of high, rugged, often precipitous, bush-clad steep-walled ravines or valleys north from Manukau Heads to Muriwai Beach, a distance of about 15 miles. In the vicinity of the heads the coast rises abruptly from sea level to heights in excess of 1,000 ft, and in places individual peaks may reach 1,500 ft. A popular scenic drive traverses the ranges from the picturesque settlement of Titirangi in the south to Swanson in the north and also provides access to the beaches of the west coast. The Waitakere Ranges are a thick accumulation (at least 1,200 ft) of marine-bedded andesitic volcanic conglomerate, breccia, tuff, and lapilli-tuff with associated pillow lavas, normal lavas, and dykes erupted during the Lower Mid-Miocene period (12–25 million years ago). The temperate climate of the ranges encourages the growth of a luxuriant forest cover of more than 250 floral species. Among the more common of the flora, which includes the giant kauri pine, are rimu, kahikatea, kowhai, tawa, manuka, ponga, tree rata, bush lawyer, and cutty grass.

Because of their comparative closeness to Auckland and unsuitability for agricultural or industrial development, at least in the highlands, the Waitakeres were early recognised as an important future watershed area. In 1900 the first of a number of water-supply projects was commenced. This culminated in the delineation and development of a watershed reserve of 10,000 acres and a total potential reservoir storage of 3,800 million gallons, giving a safe mean yield of 24 million gallons per day. Nevertheless, the explosive growth of Auckland City and urban areas, particularly since the Second World War, has resulted in the demand exceeding the supply; between 1944 and 1946 a critical review of the city's water supply revealed that the Waitakeres alone would be unable to supply future requirements.

The Waitakeres, however, continue to play an important role in the city's development, and on their lower eastern flanks at Oratia and Henderson are established the greater part of Auckland's fruit orchards and vineyards. They were also an important source of timber in the early days, and the wild bush where kiwis once roamed, the rugged coast, and surf beaches are favourite resorts for trampers, fishermen, surf skiers, and picknickers.

A literal meaning of Waitakere is Wai, water; takue, deep. Another meaning is cascading waters. It is thought that the name may possibly be a corruption of Waitekauri, a stream where the kauri grows, but it is almost certain that it was named after a chief who was murdered at the mouth of the stream.

by Barry Clayton Waterhouse, New Zealand Geological Survey, Department of Scientific and Industrial Research, Otahuhu, Auckland.