Does that symmetrical shield volcano, capped by central scoria cones, seem young to you? Rangitoto Island is a volcanic island near Auckland. This island is not just any island. It is the youngest and largest volcano in the Auckland volcanic field.
Rangitoto Island emerged from the sea around 700 years ago. Imagine the fiery drama of its birth. Two eruption phases built this iconic landmark. The first eruptions occurred around 1450 CE. The second happened about 1500 CE. This makes Rangitoto a geological youngster.
The name Rangitoto means Bloody Sky in Māori. The full name Ngā Rangi-i-totongia-a Tama-te-kapua tells a story. It speaks of the days of the bleeding of Tama-te-kapua. Tama-te-kapua was the captain of the Arawa waka. He was badly wounded here after a battle with the Tainui tribe. The battle occurred at Islington Bay.
Let’s delve into the geology of Rangitoto Island. The eruptions may have lasted only 5 to 10 years. The first phase was wet. It produced surges of volcanic ash. This ash mantled neighboring Motutapu Island. Later eruptions were dry. They built most of Rangitoto. These eruptions formed the shield and southern scoria cone. Rangitoto’s output was immense. It ejected 2.3 km3 of material. This is almost as much as all previous Auckland eruptions combined. Those eruptions occurred over nearly 200000 years.
Scientists once thought Rangitoto was active for 1000 years before its final eruptions. They found tiny volcanic glass shards in Lake Pupuke sediment. A deep hole was drilled in 2014 to find more evidence. The scientists did core a thin basalt lava flow within marine sediment dated at 6000 years old. But in 2018, research suggested Rangitoto erupted only once. This eruption occurred about 600 years ago, possibly in two phases.
The island’s structure is fascinating. The southern cone likely buries an earlier explosion crater. This crater formed during the wet phase in Waitemata Harbour. Rangitoto’s form is a gently sloping shield of overlapping lava flows. Scoria cones made of loose scoria cap the volcano’s center.
Walk through lava tubes. These cave-like tubes formed after liquid lava flowed. The lava cooled outside creating a hard crust. Molten lava continued to flow inside. The longest known cave stretches about 120 m.
Discover the unique biology of Rangitoto Island. Plants here rely on rainfall. Rangitoto boasts the largest pōhutukawa forest in the world. More than 200 tree and flower species thrive here. You will find many northern rātā trees. Also more than 40 fern species.
See the stages of ecological succession. Raw lava fields transition to scrub and sparse forests. Windblown matter and flora slowly create habitable soil. The forests are young. They don’t yet support a large bird population. But the kākā a native parrot lived here in pre-European times.
The island has a rich history. Māori iwi remember the eruption. Human footprints have been found between Rangitoto ash layers on Motutapu. Ngāi Tai consider both islands their ancestral home. Ngāti Paoa also has links with Rangitoto.
Since European colonisation, Rangitoto has served different purposes. The Crown purchased the island in 1854. It was a basalt source for construction. In 1890, it became a recreation reserve. Prison labor built roads in the 1920s and 30s. Military installations appeared during World War II. Baches small holiday houses dotted the coastline. Thirty baches remain today. They show how the island once had a permanent community.
Today, regular ferry services bring visitors to Rangitoto Island. A boardwalk leads to the summit. From there you can enjoy views of the wooded crater. A land train offers a less strenuous ascent. Sea kayak trips are also available. Note there are no campsites here.
Rangitoto Island stands as a testament to nature’s power. It reminds us of Māori legends. Its unique landscape beckons explorers.