Using this technique, called radiometric dating, scientists are able to "see" back in time.
In a related article on geologic ages (Ages), we presented a chart with the various geologic eras and their ages.
Before then, the Bible had provided the only estimate for the age of the world: about 6,000 years, with Genesis as the history book.
Hutton's theories were short on evidence at first, but by 1830 most scientists concurred that Noah's ark was more allegory than reality as they documented geological layering.
Geologist Ralph Harvey and historian Mott Greene explain the principles of radiometric dating and its application in determining the age of Earth.
As the uranium in rocks decays, it emits subatomic particles and turns into lead at a constant rate.
For example, about 1.5 percent of a quantity of Uranium 238 will decay to lead every 100 million years.
By measuring the ratio of lead to uranium in a rock sample, its age can be determined.Measuring the uranium-to-lead ratios in the oldest rocks on Earth gave scientists an estimated age of the planet of 4.6 billion years.Segment from A Science Odyssey: "Origins."Geologists have calculated the age of Earth at 4.6 billion years.For example, creationist writer Henry Morris [Morris2000, pg.147] has highlighted the fact that measurements of specimens from a 1801 lava flow near a volcano in Hualalai, Hawaii gave apparent ages (using the Potassium-Argon method) ranging from 160 million to 2.96 billion years, citing a 1968 study [Funkhouser1968].Scientists discovered that rocks could be timepieces -- literally.