Do geologists use radiometric dating

The most widely known form of radiometric dating is carbon-14 dating.

This is what archaeologists use to determine the age of human-made artifacts. The half-life of carbon-14 is only 5,730 years, so carbon-14 dating is only effective on samples that are less than 50,000 years old.

Absolute age dating is like saying you are 15 years old and your grandfather is 77 years old.

To determine the relative age of different rocks, geologists start with the assumption that unless something has happened, in a sequence of sedimentary rock layers, the newer rock layers will be on top of older ones. This rule is common sense, but it serves as a powerful reference point.

After all, a dinosaur wouldn’t be caught dead next to a trilobite.

It’s based either on fossils which are recognized to represent a particular interval of time, or on radioactive decay of specific isotopes. Based on the Rule of Superposition, certain organisms clearly lived before others, during certain geologic times.

You can learn more about fossils, dinosaurs, radiometric dating and related topics by reading through the links on the next page.

Radiometric dating isn't the only method of determining the age of rocks.

While the oldest known rocks on Earth are about 3.5 billion years old, researchers have found zircon crystals that are 4.3 billion years old [source: USGS].

Based on the analysis of these samples, scientists estimate that the Earth itself is about 4.5 billion years old.

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