Standing roughly in the centre of New Zealand’s North Island, Mt Ngauruhoe is New Zealand’s newest volcano and one of the most active (Figures 1 and 2).
It is not as well publicized as its larger close neighbour Mt Ruapehu, which has erupted briefly several times in the last five years.
This lava was not hot enough to melt olivine, so the chunks were carried along when the eruption brought lava up from the depths.
Of course the olivine inclusions dated as being old. In fact, the scientists weren't trying to date the olivine inclusions - the xenoliths.
Various creationist books mention the 1801 eruption of the Hualalai volcano in Hawaii.
They claim that scientists dated the 200 year old lava, and got the utterly bogus age of 22 million years.
Explosions of ash completed this long eruptive period. Cannon-like, highly explosive eruptions in January and March 1974 threw out large quantities of ash as a column into the atmosphere, and as avalanches flowing down the cone’s sides.
Mt Ngauruhoe is thought to have been active for at least 2,500 years, with more than 70 eruptive periods since 1839, when European settlers first recorded a steam eruption.
These flows are still distinguishable today on the northwestern and western slopes of Ngauruhoe (Figure 4).
It sits directly over the volcanic vent at the south end of the huge horseshoe-shaped crater that was blasted out of the mountain by the spectacular eruption on .1 From the crater, the dome appears as a huge steaming mound of dark, block-like rubble.
It is made of dacite, a fine-grained volcanic rock that contains a sprinkling of larger, visible crystals, like chopped fruit in a cake.