How old is the earth based on radiometric dating
He created a catalogue of strata (which all got colorful names such as Lias Blue, and Ditto White) and argued that each one represented a distinct time in Earth's history — a principle known as fossil succession.
The accumulating evidence pointed to an extraordinary new idea: that the history of Earth goes back much, much further than any human memory.
Yet, you’ve heard the news: Earth is 4.6 billion years old. That corn cob found in an ancient Native American fire pit is 1,000 years old. Geologic age dating—assigning an age to materials—is an entire discipline of its own.
In a way this field, called geochronology, is some of the purest detective work earth scientists do.
There are two basic approaches: relative age dating, and absolute age dating.
Here is an easy-to understand analogy for your students: relative age dating is like saying that your grandfather is older than you.
In Roman times, theorists guessed that Earth started around the time of the Trojan war — the earliest event in their historical record. Scientists now know the Earth is actually 4.54 billion years old, an age built on many lines of evidence from the geologic record.
This amount is often unknown and is one of the downfalls of conventional radiometric dating.
However, isochron dating bypasses this assumption, as explained below. The final condition is the number of atoms of parent and daughter isotopes remaining in the rock and can easily be measured in a lab.
[Dear Science: Where do old spacecraft go when they die?
] A century later, William Smith realized that rock layers at distant locations came from the same time period.