# 1. age of the earth (radioisotope dating vs. alternative methods)

### Index

- Are there any radioactive isotopes that are used to date fossils?
- How is radioactive dating used to date rocks?
- Why do radiometric dating methods give inflated ages?
- Why is carbon dating used to estimate the age of rocks?
- What isotopes can be used to date fossils?
- Can absolute dating be used to date fossils?
- What isotopes of carbon are used in Carbon dating?
- How did scientists use index fossils before radiometric dating?
- What is radiometric dating used to date?
- What is the basis for the age of a radioactive sample?
- What is meant by radioactive dating?
- Why do scientists reject all but the oldest dating methods?
- How old is carbon dating accurate for rocks?
- What is the importance of carbon dating in archeology?
- How do geologists determine the age of rocks?
- How is absolute age dating used in geology?

### Are there any radioactive isotopes that are used to date fossils?

Numerous radioactive isotopes exist. One system that has been very successful in dating the ages of fossils is potassium-argon dating. Potassium is an extremely common element. Although most potassium isotopes arent radioactive, one of them is, and one of its decay products is the gas argon.

### How is radioactive dating used to date rocks?

When scientists date rocks from our planet this way, the oldest dates they find are 4.5 billion years. By dating the lava flows above and below a fossil find, scientists can put exact boundaries on the maximum and minimum age of that fossil. With radioactive dating, scientists can now get within a few percentage points of the actual date.

### Why do radiometric dating methods give inflated ages?

We now have a good idea why most radiometric dating methods give inflated ages: there was at least one episode of accelerated radioactive decay in earth’s history. This is the only reasonable way to make sense of the abundance of helium found trapped in various rocks. The abundance of helium indicates that much radioactive decay has happened.

### Why is carbon dating used to estimate the age of rocks?

For whatever reason, many people have the false impression that carbon dating is what secular scientists use to estimate the age of earth rocks at billions of years. It isn’t. Carbon dating is not used on rocks, because rocks do not have much carbon in them.

### What isotopes can be used to date fossils?

Although the half-life of carbon-14 makes it unreliable for dating fossils over about 50,000 years old, there are other isotopes scientists use to date older artifacts. These isotopes have longer half-lives and so are found in greater abundance in older fossils.

### Can absolute dating be used to date fossils?

Absolute Dating. While people are most familiar with carbon dating, carbon dating is rarely applicable to fossils. Carbon-14, the radioactive isotope of carbon used in carbon dating has a half-life of 5730 years, so it decays too fast. It can only be used to date fossils younger than about 75,000 years.

### What isotopes of carbon are used in Carbon dating?

Carbon-14, the radioactive isotope of carbon used in carbon dating has a half-life of 5730 years, so it decays too fast. It can only be used to date fossils younger than about 75,000 years.

### How did scientists use index fossils before radiometric dating?

Prior to radiometric dating, evolution scientists used index fossils a. k. a. relative dating to ascertain the age of their discoveries. A paleontologist would take the discovered fossil to a geologist who would ask the paleontologist what other fossils (searching for an index fossil) were found near their discovery.

### How old is carbon dating accurate for rocks?

Because of the short length of the carbon-14 half-life, carbon dating is only accurate for items that are thousands to tens of thousands of years old. Most rocks of interest are much older than this.

### What is the importance of carbon dating in archeology?

Carbon dating is used by archeologists to date trees, plants, and animal remains; as well as human artifacts made from wood and leather; because these items are generally younger than 50,000 years. Carbon is found in different forms in the environment – mainly in the stable form of carbon-12 and the unstable form of carbon-14.

### How do geologists determine the age of rocks?

Public Domain Image, source: Christopher S. Baird. Geologists do not use carbon-based radiometric dating to determine the age of rocks. Carbon dating only works for objects that are younger than about 50,000 years, and most rocks of interest are older than that.

### How is absolute age dating used in geology?

Absolute age dating (or, radiometric dating) determines the age of a rock based on how much radioactive material it contains. Note: The following is modified from Ithaca is Gorges: A Guide to the Geology of the Ithaca Area, Fourth Edition by Warren D. Allmon and Robert M. Ross (2007).