Collect the information of geological dating and present it classroom
- How do scientists know that the Earth and meteorites formed together?
- How can a rock be dated?
- How reliable are radiometric dating methods?
- What are meteorites and why are they important?
- How do we identify meteorites and asteroids?
- How was Earth formed?
- Why do scientists reject all but the oldest dating methods?
- Is radiometric dating based on index fossils?
- Why is uranium-lead dating the most reliable method of dating?
How do scientists know that the Earth and meteorites formed together?
Rubidium-strontium, potassium-argon, uranium-lead and samarium-neodymium dating all show that the meteorites formed about 4.6 billion years ago. But detailed studies of lead isotopes in meteorites and terrestrial rocks strongly indicate that the Earth and meteorites formed at the same time.
How can a rock be dated?
Therefore, a rock can be dated by measuring how much of its original rubidium content has changed into strontium.
How reliable are radiometric dating methods?
Since 1950, radiometric methods have been developed to a very sophisticated level in several countries, including Canada. It has been demonstrated that when rocks which have led an undisturbed history are analysed, all methods reveal the same age. This uniformity demonstrates that the principle is reliable.
What are meteorites and why are they important?
The key is meteorites. Meteorites bring many different types of material from all over the solar system to Earth where scientists can study them. These materials include chondrules-tiny pieces of dust and rock that have survived from before the planets formed-and pieces of asteroids and planetesimals left behind by the planet-building process.
How do we identify meteorites and asteroids?
When asteroids land on Earth they still have the primordial composition – the stuff the Earth started out with before the heavy stuff sunk – so they are very different to normal Earth rocks. Since meteorites often have way more iron, one way to identify them is to just pick them up with a magnet.
How was Earth formed?
Scientists had thought that most of the bodies that merged to make Earth formed from a narrow zone in space and were similar to each other, belonging to a subclass of meteorites called enstatite chondrites.