Rangitoto

Today we went to the volcanic island of Rangitoto near Auckland in the Hauraki Gulf. We took a ferry at 7:30. When we arrived we started a tour with Mr. Andrew Needham, our geologist guide, to the summit of Rangitoto. He said that the volcano has erupted twice. The first time was 650 years ago during which the volcano erupted out in the Hauraki Gulf. This eruption had a rock formation of larger rocks dispersed with small fragments. The second time happened 50 years after the first eruption. This time the volcano erupted from the shallow. This eruption had rock formations had proportionally larger rocks. Mr. Needham was able to tell us this information because on the top of the summit there was an adjacent island, Motutapu, where he did his research, drilling soil cores from low-land swamps. From the sediment core he could tell that there were two volcanic eruption and he was able to tell when the volcano erupted by carbon dating twigs and organic matter. From this information, Mr.Needham was able to trace Rangitoto’s origins.

The adjacent island Motutapo also has significance to Maori people because this is where their original settlement occurred. When the volcano initially erupted the very volatile combination of magma meeting water caused a massive explosion. The second stage was calmer, as the lava flows built the island. It flowed from the source kilometers under the earth and it took a couple weeks to a month for the lava cycle to take place.

As a group we trekked our way to the top of the summit where we saw a triangulation point. This outpost was designed for defense against a Japanese attack which never happened. There were also minefields in the harbor for the same purpose.

The top of the summit had breathtaking views, so we stopped to eat lunch and relax before visiting the lava caves that were formed from the base of the magma. Overall it was a great day filled with different adventures.