Libby calculated the half-life of carbon-14 as 5568, a figure now known as the Libby half-life.
Following a conference at the University of Cambridge in 1962, a more accurate figure of 5730 years was agreed upon and this figure is now known as the Cambridge half-life.
However, it is also used to determine ages of rocks, plants, trees, etc. When the sun’s rays reach them, a few of these particles turn into carbon 14 (a radioactive carbon).
The highest rate of carbon-14 production takes place at altitudes of 9 to 15 km (30,000 to 50,000 ft).
In the same rock, right alongside the fossil mussels, are fragments of coalified wood.
Some time after I took my samples, I discovered the same sandstone, appropriately described as coming from Mägenwil, exhibited in the ‘Geologisch-Mineralogische Austellung der ETH’ in Zürich—naturally, also labelled ‘20 million years old’.
Mainstream geologists would never think of trying to get a radiocarbon (C) date for the coalified wood in this Mägenwil sandstone, because anything that old should not be datable by this method.magazine has been continuously published since 1978, we are publishing some of the articles from the archives for historical interest, such as this.For teaching and sharing purposes, readers are advised to supplement these historic articles with more up-to-date ones suggested in the Related Articles and Further Reading below.So anything which really millions of years old would have no detectable radiocarbon left, and would register as giving an ‘infinite radiocarbon age’.Carbon dating, as it is often called, is thus never used to date ‘old’ fossils (which usually have no organic carbon left anyway).
The amount of carbon-14 gradually decreases through radioactive beta decay with a half-life of 5,730 years.