Answer:
The quantities that we can measure are the decay rate of radioactive isotopes contained in the rocks or minerals
Explanation:
Rocks and minerals containing radioactive materials can be dated Radiometrically. This process is known as Radiometric dating or Radioactive dating.
Radiometric dating is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes. Different methods of radiometric dating can be used to estimate the age of a variety of natural materials.
Examples are:
Radioactive Decay method
The methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. So, they do this by giving off radiation. This process by which an unstable atomic nucleus loses energy by releasing radiation is called radioactive decay. The thing that makes this decay process so valuable for determining the age of an object is that each radioactive isotope decays at its own fixed rate, which is expressed in terms of its half-life. So, if you know the radioactive isotope found in a substance and the isotope's half-life, you can calculate the age of the substance.
Half-Life
Half life is the time required for a radioactive materials quantity to half of its original value.
Uranium-Lead Dating
uranium-lead dating can be used to find the age of a uranium-containing mineral. It works because we know the fixed radioactive decay rates of uranium-238, which decays to lead-206, and for uranium-235, which decays to lead-207. So, we start out with two isotopes of uranium that are unstable and radioactive. They release radiation until they eventually become stable isotopes of lead.
These two uranium isotopes decay at different rates. In other words, they have different half-lives. The half-life of the uranium-238 to lead-206 is 4.47 billion years. The uranium-235 to lead-207 decay series is marked by a half-life of 704 million years. These differing rates of decay help make uranium-lead dating one of the most reliable methods of radiometric dating because they provide two different decay clocks. With this, the age of the sample(That is rock or mineral) under consideration can be determined.
Answer:
Explanation:
The absolute dates for rocks are obtained with radiometric methods. These use radioactive minerals in rocks as geological clocks. The atoms of some chemical element have different forms called isotopes. These break down over time in a process called radio active decay. Each original isotope called the parent gradually decay to form a new isotope called the daughter. Each isotope is identified with what we called mass number. When parent Uranium -238decays for example, it produces sub atomic particles, energy and daughter lead-206.
Measuring isotopes is particularly useful for dating igneous and some metamorphic rocks, but not sedimentary rock. Sedimentary rock is made of particles derived from other rocks so measuring isotope would date the original rock materials, not the sediments they ended with. We can also use mass spectrometer to measure the amount of isotopes in rocks. For example, fission track dating measures the microscopic marks left in crystal by sub atomic particles from decaying isotopes.
