Radiometric dating of planets
He also recognized that the rivers of northern Italy, flowing south from the Alps and emptying into the sea, had done so for a very long time.With the exception of a few prescient individuals such as Roger Bacon (Leonardo da Vinci (1452–1519), no one stepped forward to champion an enlightened view of the natural history of the Earth until the mid-17th century.Leonardo seems to have been among the first of the Renaissance scholars to “rediscover” the uniformitarian dogma through his observations of fossil marine organisms and sediments exposed in the hills of northern Italy.Following from this observation, Steno concluded that the Tuscan rocks demonstrated superpositional relationships: rocks deposited first lie at the bottom of a sequence, while those deposited later are at the top.
This is the crux of what is now known as the principle of superposition.
Loosely stated, the principle says that the various natural phenomena observed today must also have existed in the past (see below The emergence of modern geologic thought: Lyell’s promulgation of uniformitarianism).
Radiometric dating of planets comments