The rate of decay is known and constant. The higher the proportion of argon-40, the older the rock. A mass spectrometer measures these ratios to establish a date. The older procedure known as potassium-argon dating-hitherto the best way of determining the age of something more than a few tens of thousands of years old-is done in two steps, requiring two samples. First, a chemical process determines how much potassium is present. Then a mass spectrometer looks at the second sample to see how much potassium has altered radioactively to become its daughter argon. The procedure suffers from the effects of weathering, which occur not only on the surface of rock but from grain to grain within. Argon slips away from zakelijke energie weathered material, thus changing its overall ratio to potassium and making any date determined by this method all the more approximate. Argon-argon dating is accomplished in the microscopic core of a single grain, beyond even the faintest disturbances of weather. The newer method is significantly more consistent and accurate than the older one. Results have shown-notably among the New England Seamounts-that where many potassium-argon dates fall into general approximation with Morgan’s calculations, the dates derived by argon-argon follow the track exactly. Eighty million years ago, in the Campanian age of late Cretaceous time, Great Meteor would have underlain the AmericanAfrican plate boundary, the Mid-Atlantic Ridge. Since then, Great Meteor has cut a gentle zakelijke energie vergelijken curve southward through the African Plate. From late Cretaceous, Paleocene, and Eocene time, the path is as well defined as it is on the American side. After the Eocene, the hot spot made the big seamount that bears its name. Then it began to go cold, to evanesce, to fade like a shooting star.