Ah, thanks for the explanation, Helen. Actually® WO'N and I were posting simultaneously, so I can't claim any credit for, er, wit.

Meanwhile, here's one for you, stales:

"GEOLOGY, n.
The science of the earth's crust -- to which, doubtless, will be added that of its interior whenever a man shall come up garrulous out of a well. The geological formations of the globe already noted are catalogued thus: The Primary, or lower one, consists of rocks, bones or mired mules, gas-pipes, miners' tools, antique statues minus the nose, Spanish doubloons and ancestors. The Secondary is largely made up of red worms and moles. The Tertiary comprises railway tracks, patent pavements, grass, snakes, mouldy boots, beer bottles, tomato cans, intoxicated citizens, garbage, anarchists, snap-dogs and fools."