The earth has been determined by radiometric dating to be the cindy margolis dating project

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.This spawned several earnest — if not entirely successful — attempts to determine the age of the Earth based on ongoing natural processes.One calculated how long it would take rivers to deliver enough dissolved minerals to the ocean to give it its current saltiness (answer: 90 million to 100 million years).

The "begats" in the Bible were another source for estimates: In the 17th century, Ireland's Archbishop James Ussher reconstructed the genealogy of biblical figures and declared that Earth was created at 6 p.m. The modern effort to understand the age of the planet started with Nicholas Steno, a Danish anatomist and geologist who was among the first to realize that fossils are the remains of living creatures.The age of the planet, though, was important to Charles Darwin and other evolutionary theorists: The biological evidence they were collecting showed that nature needed vastly more time than previously thought to sculpt the world.A breakthrough came with the discovery of radioactivity at the beginning of the 1900s.Here's how that works: The nuclei of radioactive elements decay — or spontaneously break down — at predictable rates.For example, half of a given batch of uranium will decay into lead every 710 million to 4.47 billion years, depending on the isotope used (this number is termed the element's “half-life").