A way of finding out how old volcanic rock is.
Potassium/argon dating
Fact of the Day
In the Middle Ages, land could be held from the monarch in return for a service, such as holding the king's head as he crossed the Channel by boat.
Quote of the Day
"Truly, when the day of judgement comes, it will not be a question of what we have read, but what we have done.
"
~ Thomas à Kempis, 15th century
On This Day
43 BCE The assassination of Cicero, requested by Marc Antony. When his head was delivered to Anthony, his wife, Fulvia, spat on it and jabbed hairpins into his tongue.
1732 The Theatre Royal, now known as the Covent Garden Opera House, opened with a performance of the Beggar's Opera.
1787 Delaware became the first state of the modern United States.
1817 Rear-Admiral William Bligh died. He had been captain of HMS Bounty during the mutiny.
1941 The Japanese launched a surprise attack on the American naval base a Pearl Harbour, Hawaii, killing 2,403.
1982 Charles Brooks Jr became the first person to be executed by lethal injection, with a huge dose of 'truth serum'