Then Richard Leakey found a skull (called KNM-ER 1470) the KBS tuff, a skull that looked far too modern to be 3 million years old.
So Curtis and others redated the KBS tuff using selected pumice and feldspar samples, and obtained an age of 1.82 million years.
Using new samples of feldspar and pumice they ‘reliably dated’ the tuff at 2.61 million years, which agreed nicely.
Later, this date was confirmed by two other dating methods (paleomagnetism and fission tracks), and was widely accepted.
However, scientists can look at the decay of other elements in these objects allowing them to date them up to 2.2 billion years.
Men go abroad to wonder at the heights of mountains, at the huge waves of the sea, at the long courses of the rivers, at the vast compass of the ocean, at the circular motions of the stars; and they pass by themselves without wondering.
Mountains have been built and eroded, continents and oceans have moved great distances, and the Earth has fluctuated from being extremely cold and almost completely covered with ice to being very warm and ice-free.
These changes typically occur so slowly that they are barely detectable over the span of a human life, yet even at this instant, the Earth's surface is moving and changing.
Using the potassium-argon method, Fitch and Miller were the first to measure the age of the tuff.
So by 1980 there was a new, remarkably concordant date for the KBS tuff, and this became the one that was widely accepted.
Despite seeming like a relatively stable place, the Earth's surface has changed dramatically over the past 4.6 billion years.
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