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).
The 18 August flow was more than 18 m (55 feet) thick and still warm almost a year after congealing.
Geologists, paleontologists, archeologists, and anthropologists use a statistical process like radioactive isotope decay to date objects through a method called radioactive dating (also known as radiometric dating).
To learn more about that method, check out the geology science project How Old Is That Rock?
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).If you want a Project Idea with full instructions, please pick one without an asterisk.Have you ever wondered how it's possible to so accurately date ancient artifacts?For example, you can’t find the remaining amount of an isotope as 7.5 half-lives by finding the midpoint between 7 and 8 half-lives.This decay is an example of an exponential decay, shown in the figure below.