Potassium argon dating volcanic ash row can not be located for updating
However, Mt Ngauruhoe is an imposing, almost perfect cone that rises more than 1,000 metres (3,300 feet) above the surrounding landscape to an elevation of 2,291 m (7,500 feet) above sea level1 (Figure 3).
Eruptions from a central 400 m (1,300 foot) wide crater have constructed the cone’s steep (33°) outer slopes.
Following death, however, no new carbon is consumed.
The first lava eruption seen by Europeans occurred in 1870.3 Then there were ash eruptions every few years until a major explosive eruption in April–May 1948, followed by lava flowing down the northwestern slopes in February 1949.4 These flows are still distinguishable today on the northwestern and western slopes of Ngauruhoe (Figure 4).
Argon gas, brought up from deep inside the earth within the molten rock, was already present in the lavas when they cooled.
We know the true ages of the rocks because they were observed to form less than 50 years ago.
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.