In the decades that followed, scientists made important new discoveries about the structure and behavior of atoms, and they refined their existing dating techniques.
More recently, they have developed a number of new methods.
Indeed, findings presented earlier this year suggest that infant Earth may have been ready to support life far earlier than previously thought.
Uranium-lead dates for a single zircon crystal found in the oldest sedimentary rock yet known suggest that by 4.4 billion years ago our planet already had already cooled enough to have a crust.
Routine contamination levels in the lab for zircon analyses have been reduced to less than a trillionth of a gram of lead, permitting U-Pb dating of single crystals of zircon finer than a grain of sand and of almost any age.
Geologists, paleontologists and archaeologists have pieced together a fairly detailed account of how Earth and its inhabitants evolved.
Now, nearly 100 years after Boltwood's groundbreaking work, it is estimated that Earth formed at least twice as long ago as he had claimed.
Researchers can thus determine the amount of time that has passed since the buried crystal was last exposed to heat.
Some use radioactive isotopes; others take advantage of different phenomena, such as thermoluminescence and electron spin resonance.
Still others, like amino acid racemization, show promise but have not yet taken wing.
Argon dating can also be used to date materials as young as 10,000 years and as old as billions of years.
Uranium and lead isotopes take us back farther still.