Age of a rock using radiometric dating first base second base third base fourth base dating

Droughts and other variations in the climate make the tree grow slower or faster than normal, which shows up in the widths of the tree rings.

Radioactive materials in Earth's interior provide a steady source of heat.

Calculations of Earth's age using radioactive decay showed that Earth is actually much older than Thomson calculated.

Another example of yearly layers is the deposition of sediments in lakes, especially the lakes that are located at the end of glaciers.

Rapid melting of the glacier in the summer results in a thick, sandy deposit of sediment.

But determining the absolute age of a substance (its age in years) is a much greater challenge.

To accomplish this, scientists use a variety of evidence, from tree rings to the amounts of radioactive materials in a rock.

These thick layers alternate with thin, clay-rich layers deposited during the winter.

The resulting layers, called varves, give scientists clues about past climate conditions.

While tree rings and other annual layers are useful for dating relatively recent events, they are not of much use on the vast scale of geologic time.

During the 18th and 19th centuries, geologists tried to estimate the age of Earth with indirect techniques.

The discovery of radioactive materials did more than disprove Thomson's estimate of Earth's age.

Tags: , ,